Class 9

9th Standard English Unit 4 Poem The Spider and the Fly Book Back Answers

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The Spider and the Fly 9th Standard English 4th Lesson Question and Answer

The Spider and the Fly Warm Up:

Samacheer Kalvi 9th English Solutions Poem Chapter 4 The Spider and the Fly

Question 1.
How will you make him or her eat them?
Answer:
I will explain the nutritious value of these vegetables and how ii helps in maintaining good health.

Question 2.
What are all the flattering or tempting words you might use to convince them?
Answer:
I will say that if they eat these vegetables, it will make them healthy and smart. I will convince them by explaining that eating vegetables is a good habit and that they will be called obedient and disciplined children if they listen to good advice.

3. Work in pairs and enact that moment in front of your classmates.

The Spider and the Fly Textual Questions

A. Read the following lines from the poem and answer the questions in a sentence or two.

1. “The way into my parlour is up a winding stair,
And I’ve many curious things to show when you are there ”

Question (a).
How to reach the spider’s parlour.
Answer:
Through a winding stair, you can reach the spider’s parlour.

Question (b).
What will the fly get to see in the parlour?
Answer:
The fly will get to see many curious things in the parlour.

2. “Oh no, no, ” said the little Fly, “kind Sir, that cannot be,
I’ve heard what s in your pantry, and I do not wish to see! ”

Question (a).
Is the fly willing to enter the spider’s pantry?
Answer:
No, the fly is not willing to enter the parlour.

Question (b).
Can you guess what was in the pantry?
Answer:
Only remains of dead flies may be found in the pantry.

3. “Sweet creature! ” said the Spider, “you’re witty and you’re wise,
How handsome are your gauzy wings, how brilliant are your eyes!”

Question (a).
List the words used by the spider to describe the fly.
Answer:
Handsome, gauzy (wings), brilliant (eyes) are the words the spider used to describe the fly.

Question (b).
Why does the spider say that the fly is witty?
Answer:
The spider calls the fly witty because the fly is clever to avoid entering the web.

4. The Spider turned him round about, and went into his den,
For well he knew the silly Fly would soon come back again:

Question (a).
Why is the poet using the word ‘den’ to describe the spider’s web?
Answer:
Wild animals live in their dens. Spider also has its web as its dwelling place. So the poet uses the word ‘den’.

Question (b).
Why was the spider sure that the fly would come back again?
Answer:
The spider has flattered the fly of its beauty, so he was sure it would come back again.

5. With buzzy wings, she hung aloft, then near and nearer drew,
Thinking only of her brilliant eyes, and green and purple hue-

Question (a).
Who does she refer to? ON)
Answer:
‘She’ refers to the fly.

Question (b).
What was she thinking of? 0
Answer:
She was thinking of her beautiful eyes and the colours of her wings.

6. And now dear little children, who may this story read,
To idle, silly flattering words, I pray you never give heed:

Question (a).
Who does ‘I’ refer to?
Answer:
I refer to the poet.

Question (b).
What is the advice given to the readers?
Answer:
Never listen to idle, silly flattering words, “is the advice given to the readers”.

Additional Questions

1. “I’m sure you must be weary, dear, with soaring up so high;
Will you rest upon my little bed?” said the spider to the fly.

Question (a).
Why is the fly weary?
Answer:
The fly is weary because of the fact that it flies high up in the sky.

Question (b).
What does the spider ask the fly?
Answer:
The spider asks the fly if it will rest on his bed.

2. So he wove a subtle web, in a little corner sly,
And set his table ready to dine upon the fly.

Question (a).
What is meant by subtle?
Answer:
Subtle means are delicate or faint or mysterious.

Question (b).
Pick out the rhyming words.
Answer:
The rhyming words are ‘sly’ and ‘fly’.

3. “There are pretty curtains drawn around, the sheets are fine and thin,
And if you like to rest awhile, I’ll snugly tuck you in.”

Question (а).
What do you understand by the term, ‘snugly’?
Answer:
‘Snugly’ means to be secured or have a feel of comfort.

Question (b)
Mention the figure of speech in the above lines.
Answer:
Assonance is the figure of speech employed.

For example:
The sound of ‘aw’ in drawn and around.
The vowel sound in snugly and tuck.

4. I have within my pantry good store of all that’s nice;
I’m sure you’re very welcome; will you please to take a slice?”

Question (a).
What is a pantry?
Answer:
A pantry is a storeroom for foods or wines.

Question (b).
Give the rhyming word for nice.
Answer:
The rhyming word for nice is ‘slice’.

5. Alas, alas! how very soon this silly little fly,
Hearing his wily flattering words, came slowly flitting by;

Question (a).
Why is the little fly silly?
Answer:
The little fly is silly because it came back enticed by the spider’s flattering words.

Question (b).
What is ‘wily’?
Answer:
‘Wily’ is cunning.

B. Complete the summary by filling in the spaces with suitable words.

The poem begins with the spider’s (1) …………………. of the fly. He (2) …………….. to the fly to come into its home. The spider describes his parlor as the (3) …………………. one. The spider kindles the curiosity of the fly so that she may enter his home. Fortunately, the fly was (4) ………………… and refused to get into his home. Now the spider pretends to be a (5) …………………. and asks her to come and rest in his home. He offers her (6) ……………………. and a (7) ………………….. to rest. This time also the fly (8) ………………… the spider’s offer very politely. The next weapon that the spider uses is (9) …………………. The spider praises the (10) ……………….. and (11) …………………. of the fly and also praises her (12) …………………….. He invites her to look at herself in the (13) ………………………. which is in his parlour. The fly is (14) …………….. by the words of the spider and she falls a (15) …………………… to her (16) ………………….
Answers

1. welcoming
2. reaches out
3. prettiest
4. wise/intelligent
5. friend
6. sheets
7. bed
8. declines
9. flattery
10. wings
11. eyes
12. crest
13. looking-glass
14. flattered
15. prey
16. enticement/invitation

C. Answer the following questions in about 80-100 words.

Question 1.
Write a character sketch of the spider.
Answer:
This poem takes us through a spider’s ultimately successful attempts at enticing a fly into its web. The spider is cunning in capturing its victim. It ensnares the fly through the use of seduction and flattery. In stanza one, it does its best to trap the fly into its parlour with the promises of pretty things to see. Next, it tries a different tactics, offering the fly a pretty and a comfortable place to sleep, and lovely food. Finally, it tries to flatter the fly by praising its beauty and traps the fly in his den.

Question 2.
What happens if we fall prey to flattery? Give instances from the poem ‘The Spider and the Fly’.
Answer:
If we fall prey to flattery, we have to face evil consequences, just like the fly who falls prey to the spider’s flattery and seduction. The spider uses different tactics to entice the fly into its web. It invites the fly into its parlour with the promises of pretty things to see. When the fly refuses, it entices him by offering a pretty, comfortable bed and lovely food. When the fly refuses again, finally it flatters the fly for its beautiful appearance. The fly gets flattered and gets trapped in its den. This poem teaches us that we should be cautious against those who use flattery and charm to disguise their true evil intentions.

Question 3.
In your own words, give a detailed description of:
(a) The Spider’s Parlour.
Answer:
The Spider’s Parlour had winding stairs. It is the prettiest parlour that had ever been seen by the fly. It has been filled with many pretty things, which would arouse the curiosity of the fly. There are also pretty curtains, whose sheets are fine and thin. It had a pretty and comfortable bed.

(b) The Fly’s Appearance
Answer:
The fly had gauzy wings and brilliant eyes. But the spider flattered it saying that it had pearl and silver wings, green and purple body and its antenna is like a crown on him.

Additional Questions:

1. What are the four ways by which the spider lures the fly?
There are four ways by which the spider lures the fly:

• The spider invites the fly to his home.
• The spider pretends to be concerned over the weary fly and offers his bed.
• He tries to influence the fly to come and have a look into his pantry.
• He compliments the fly’s intelligence, gauzy wings, and bright eyes.

At last, the spider is successful in luring the fly.

Appreciate The Poem
Figures of speech

1. Consonance: Repetition of similar consonant sounds in the neighbouring words.
Ex: “T is the prettiest little parlour that ever you did spy;
Pick out one more instance of consonance from the poem.
Hearing his wily, flattering words, came slowly flitting by;
So he wove a subtle web, in a little corner sly.

2. Assonance: Repetition of similar vowel sounds in the neighbouring words.
Ex: “T is the prettiest little parlour that ever you did spy;
Pick out one more instance of consonance from the poem.
The spider tuned him roundabout and went into his den,
“I’m sure you must be weary, dear, with soaring up so high.”

3. Anaphora: Repetition of a word or a phrase at the beginning of a sequence of sentences, paragraphs and lines.
Ex: How handsome are your gauzy wings, how brilliant are your eyes!
Identify the figures of speech.
“Your eyes are like the diamond bright, but mine are dull as lead! ’’
A simile is the figure of speech.

4. Alliteration: Repetition of consonant sounds at the beginning of words.
Pick out the words in alliteration.
“Sweet creature! ” said the Spider, “you’re witty and you ’re wise,”
Sweet – Spider; and witty – wise are alliterated.

Listening

D. Listen to the passage and fill in the blanks with appropriate answers.

(For listening to the passage refer to our website www.fullcircleeducation.in) Trust is one of the most important things anyone can have in a relationship because trust is what makes the foundation of a relationship. Without trust there is no relationship at all because everything you do or make of the relationship will be based on truth. Trust is a very rare thing to find and if you are able to give it in return, your life is so much better and more fulfilling for everyone involved. Trusting people can hurt sometimes because they betray you, but you learn from the situation and move on to the next adventure in your life. Just don’t let small bumps in the road throw you back to not trusting and being cold. Simply keep moving forward and you will have a wonderfully fulfilling life that will be filled with good people that care and are trustworthy.

1. Without trust, there is no………………
2. …………….. is a very rare thing to find in life.
3. When people betray you learn from the………………………
4. Don’t let ……………….. on the road…………………….
5. If we keep moving forward you will have a wonderfully……………………..

Answers

1. relationship
2. Truth
3. situation
4. small bumps; to make you cold
5. fulfilling life

Speaking:

E. The cunning spider was waiting for a chance to pull the fly into its web and it used all the possible ways to trap her. Have you ever been trapped by flattery to do something you did not want to do? Discuss in pairs and share your experience in the class.

A small token of appreciation definitely rejuvenates our energy. But the escalation of mood which flattery brings is quite different. It makes you land in cloud nine. Sadly one realizes the consequences at the end of all turmoil. As in the poem, it may also go to the level of costing one’s life. This kind of flattery has led me to take the wrong decision in my life once. I was born and brought up in a village. When I completed my 6th standard, my parents got an opportunity of moving to Chennai and I was all excited about it.

My cousin, who was not happy with this, came and persuaded me to stay in the village. She said that I was very brilliant and would be a role model to all other students, but in Chennai, I wouldn’t be appreciated so much. She said I would be happier, healthier and would have more fun here rather than in the city since all the village people really liked me. Due to her influence, I asked my parents to leave me and go to Chennai.

Before 1 could realize that it was a trap, my parents had left and I had to stay in the village for another 2 years missing my parents and the luxuries of Chennai city. This poem reminded me of that experience from which I have learned my lesson, not to fall prey to flattery.

Writing:

F. The fly gives into flattery and becomes the spider’s prey. If you are asked to give a happy ending to the poem, how will you save the fly? Write in your own words.

Finally, the fly, mesmerized by the words spoken by the spider about her beauty, flies towards the web. But before she could enter it, the fly’s friend arrives and sees what a dreadful trap she is going .to fall into. She immediately comes in front of her and stops her from entering the web. The fly regaining her consciousness realizes what a foolish thing she was going to do and thanks to her friend for saving her life.

The Spider and the Fly by Mary Botham Howitt About The Poet:

Mary Botham Howitt (1799 – 1888) was an English poet. She was born at Coleford, in Gloucestershire. She was home-schooled and read widely. She commenced writing verses at an early age. In 1821, she married William Howitt and began a career of joint authorship with him. William and Mary were associated with many important literary figures of the day including Charles Dickens, Elizabeth Gaskell, and Elizabeth Barrett Browning. In 1837, she started writing her well-known tales for children, a long series of books which met with signal success. She received a silver medal from the Literary Academy of Stockholm. Together with her husband William Howitt she wrote over 180 books.

The Spider and the Fly Summary:

‘The Spider and the Fly’ teaches the reader not to be misled by flattery and be trapped. Here a spider lures a fly to enter its web, upon which he can feast upon her. He invites the little fly to enter its pretty parlour using the winding stairs since there are so many curious things to see there. The fly refuses by saying that whoever enters the parlour can never be freed.

The spider further persuades the fly saying that she must be tired by flying so high and that she can come and take rest in his bed. For this, the fly replies that she has heard that whoever sleeps in his bed never wakes up again. The spider then tries to tempt the fly asking her to come and see his pantry where all nice things are available for her to taste and see.

The fly answers the spider saying I has already heard what is available in your pantry and I am not willing to see them. When all the attempts failed, the spider praises the fly saying that she is very witty and wise, with her gauzy wings and brilliant eyes. He asks her to come and have a look in the mirror that he has in his parlour. For this the fly thanks him and says she will come some other day. The spider knowing that the fly has been flattered, and will surely come to his web, makes ready his table to dine upon the fly.

Then the spider comes out and starts to sing merrily describing the beautiful features of the fly once again comparing it with his. After hearing these words, the fly cannot resist herself from thinking about her beauty and falls into the spider’s web. The spider quickly grabs her and traps her in his den from where she never comes out. The poet now asks the little children not to fall a prey to such silly, flattering words and also, never listen to an evil counselor.

The Spider and the Fly Glossary:

Textual:
counsellor – a person who advises
flattering – to praise or compliment insincerely
pantry – a room where beverages, food, dishes are stored
parlour – a tidy room in a house used for entertaining guests
subtle – delicate or faint and mysterious
weary – very tired, especially from hard work
winding – a twisting movement or course

Samacheer Kalvi 9th English Book Solutions Poem

• Stopping by Woods on a Snowy Evening Book Back Answers
• A Poison Tree Book Back Answers
• On Killing a Tree Book Back Answers
• The Spider and the Fly Book Back Answers
• The River Book Back Answers
• The Comet Book Back Answers
• The Stick-together families Book Back Answers

You can Download Samacheer Kalvi 9th Science Book Solutions Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 8 Sound

Samacheer Kalvi 9th Science Sound Textbook Exercises

I. Choose the correct answer:

Question 1.
Which of the following vibrates when a musical note is produced by the cymbals in a orchestra?
(a) stretched strings
(b) stretched membranes
(c) air columns
(d) metal plates
Answer:
(a) stretched strings

Question 2.
Sound travels in air:
(a) if there is no moisture in the atmosphere.
(b) if particles of medium travel from one place to another.
(c) if both particles as well as disturbance move from one place to another.
(d) if disturbance moves.
Answer:
(b) if particles of medium travel from one place to another.

Question 3.
A musical instrument is producing continuous note. This note cannot be heard by a person having a normal hearing range. This note must then be passing through ………….
(a) wax
(b) vacuum
(c) water
(d) empty vessel
Answer:
(d) empty vessel

Question 4.
The maximum speed of vibrations which produces audible sound will be in ……………..
(a) seawater
(b) ground glass
(c) dry air
(d) Human blood
Answer:
(a) seawater

Question 5.
The sound waves travel faster
(a) in liquids
(b) in gases
(c) in solids
(d) in vacuum
Answer:
(c) in solids

II. Fill in the blanks.

1. Sound is a ………… wave and needs a material medium to travel.
2. Number of vibrations produced in one second is …………..
3. The velocity of sound in solid is …………. than the velocity of sound in air.
4. Vibration of object produces …………..
5. Loudness is proportional to the square of the …………..
6. …………… is a medical instrument used for listening to sounds produced in the body.
7. The repeated reflection that results in persistence of sound is called ……………..

Answer:

1. longitudinal
2. frequency of wave
3. faster
4. Sound
5. amplitude
6. ECG
7. reverberation

III. Match the following.

Column – I	Column – II
(a) Tuning fork	(i) The point where density of air is maximum
(b) Sound	(ii) Maximum displacement from the equilibrium position
(c) Compressions	(iii) The sound whose frequency is greater than 20,000 Hz
(d) Amplitude	(iv) Longitudinal wave
(e) Ultrasonics	(v) Production of sound

Answer:
(a) (v)
(b) (i)
(c) (iv)
(d) (ii)
(e) (iii)

IV. Answer in brief.

Question 1.
Through which medium sound travels faster, iron or water? Give reason.
Answer:
Sound travels faster through iron as solids are packed together tighter than liquids and gases.

Question 2.
Name the physical quantity whose SI unit is ‘hertz’. Define.
Answer:
The SI unit of frequency is hertz (Hz). The number of vibrations (complete waves or cycles) produced in one second is called frequency of the wave.

Question 3.
What is meant by supersonic speed?
Answer:
When the speed of any object exceeds the speed of sound in air (330 m s-1) it is said to be travelling at supersonic speed.

Question 4.
How does the sound produced by a vibrating object in a medium reach your ears?
Answer:
When an object vibrates, it forces the neighbouring particles of the medium to vibrate. These vibrating particles then force the particles adjacent to them to vibrate. In this way vibrations produced by an object are transferred till it reaches the ear.

Question 5.
You and your friend are on the moon. Will you be able to hear any sound produced by your friend?
Answer:
No, as there is no medium on moon for the sound to travel.

V. Answer in detail.

Question 1.
Describe with diagram, how compressions and rarefactions are produced.
Answer:
Sound is also a longitudinal wave. Sound can travel only when there are particles which can be compressed and rarefied. Compressions are the regions where particles are crowded together. Rarefactions are the regions of low pressure where particles are spread apart. A sound wave is an example of a longitudinal mechanical wave. Below figure represents the longitudinal nature of sound wave in the medium.

Question 2.
Verify experimentally the laws of reflection of sound.
Answer:
The laws of reflection are:

• The angle in which the sound is incident is equal to the angle in which sound is reflected.
• Direction of incident sound, direction of the reflected sound and the normal are in the same plane.

Take two metal tubes A and B. Keep one end of each tube on a metal plate as shown in figure. Place a wrist watch c at the open end of the tube A and interpose a cardboard between A and B. Now at a particular inclination of the tube B with the cardboard, ticking of the watch is clearly heard. The angle of reflection made by the tube B with the cardboard is equal to the angle of incidence made by the tube A with the cardboard.
For example, if the angle of incidence is 20° on the left side of a protractor (see figure arrangement), the angle of reflection at which we are able to hear the sound clearly will also be at 20° on the right side of the protractor.
∴ ∠ i = ∠ r    ➝ verifying Law I
We will also further observe that pipe 1, pipe 2 i.e, the incident ray, reflected ray and the normal lie on the same plane, verifying law II.

Question 3.
List the applications of sound.
Answer:
Applications of Ultrasonic Sound
1. Cleaning Technology :
Minute foreign particles can be removed from objects placed in a liquid bath by ultrasonic sound waves.

2. Industry:
To detect cracks and flaws in metal blocks.

3. Medicine

• Echocardiography:
  Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart.
• In Kidney :
  To break small stones formed in the kidney into fine grains, which is flushed out with urine.

Question 4.
Explain how do SONAR works?
Answer:
SONAR is the abbreviation for Sound Navigation And Ranging.

• SONAR consists of a transmitter and a detector and they are installed at the bottom of boats and ships.
• The Transmitter produces and transmits the ultrasonic waves to travel through water.
• The detector senses the ultrasonic waves that reflected back after striking the object.
• It converts ultrasonic waves into electrical signals which can be interpreted.
• By knowing the speed of sound in water
• and time interval (t) between transmission and reception of ultrasonic sound, the distance of the object can be calculated by, 2d = v x t
• This method is called the echo-ranging.

VI. Numerical problem.

Question 1.
The frequency of a source of sound is 600 Hz. How many times does it vibrate in a minute?
Answer:
The number of vibrations (complete waves or cycles) produced in one second is called frequency of the wave.
Hence, in one minute 600 x 60 vibrations are produced = 36000 (Need clarification)

Question 2.
A stone is dropped from the top of a tower 750 m high into a pond of water at the base of the tower. When is the splash heard at the top?
(Given g = 10 m s^{– 2} and speed of sound = 340 ms^{– 1})
Height = 750m
h = ut + 0.5 gt²
The initial velocity is 0
750 = 0.5 × 10 × t²
t = 10sec
Speed of sound is 340m/sec
So, time taken to travel 750m upwards is,
\(\frac { 750 }{ 340 }\) = 2.20s
time taken = 10 + 2.20 = 12.2 sec.

Samacheer Kalvi 9th Science Sound In Text Problems

Question 1.
A sound wave has a frequency of 2 kHz and wavelength of 15 cm. How much time will it take to travel 1.5 km?
Solution:
v = nλ
n = 2 kHz = 2000Hz
λ = 15 cm = 0.15 m
0.15 × 2000 = 300ms^{– 1}
Time(t) = \(\frac{\text { Distance (d) }}{\text { Velocity (v) }}\)
The sound will take 5 s to travel a distance of 1.5 km.

Question 2.
What is the wavelength of a sound wave in air at 20° C with a frequency of 22 MHz?
Solution:
λ = v/n
Here, v = 344 m s^{– 1}
n = 22 MHz = 22 × 10⁶ Hz
λ = \(\frac { 344 }{ 22 }\) × 10⁶ = 15.64 × 10⁶ m = 15.64 µm.

Question 3.
A man fires a gun and hears its echo after 5 s. The man then moves 310 m towards the hill and fires his gun again. If he hears the echo after 3 s, calculate the speed of sound.
Solution:
Distance (d) = velocity (v) × time (t)
Distance travelled by sound when gun fires first time, 2d = v × 5 …………. (1)
Distance travelled by sound when gun fires second time, 2d – 620 = v × 3 …………… (2)
Rewriting equation (2) as,
2d = (v × 3) + 620 ……………. (3)
Equating (1) and (3), 5v = 3v + 620
2v = 620 .
Velocity of sound, v = 310 m s^{– 1}

Question 4.
A ship sends out an ultrasound that returns from the seabed and is detected after 3.42 s.
If the speed of ultrasound through seawater is 1531m s^{– 1}, what is the distance of the seabed from the ship?
Solution:
We know, distance = speed × time
2d = speed of ultrasound × *time
2d = 1531 × 3.42
∴ d = \(\frac{5236}{2}\) = 2618 m
Thus, the distance of the seabed from the ship is 2618 m or 2.618 km.

Samacheer Kalvi 9th Science Sound Additional Questions

I. Answer the following questions.

Question 1.
“Sound needs a medium for propagation”. Justify with an experiment.
Answer:

Sound needs a material like air, water, steel, etc. for its propagation. It cannot travel through vacuum. This can be demonstrated by the Bell-Jar experiment.

An electric bell and an airtight glass jar are taken. The electric bell is suspended inside the airtight jar. The jar is connected to a vacuum pump. If the bell is made to ring, we will be able to hear the sound of the bell. Now when the jar is evacuated with the vacuum pump, the air in the jar is pumped out gradually and the sound becomes feebler and feebler. We will not hear any sound, if the air is fully removed (if the jar has vacuum).

Question 2.
Name the characteristics that describe a sound.
Answer:
A sound wave can be described completely by five characteristics viz – amplitude, frequency, time period, wavelength and velocity or speed.

Question 3.
What does the intensity of sound heard at a place depend on?
Answer:
The intensity of sound heard at a place depends on the following factors;

1. Amplitude of the source
2. Distance of the observer
3. Surface area of the source
4. Density of the medium
5. Frequency of the source.

Question 4.
Why is sound wave called longitudinal wave?
Answer:
As the vibration of the particles of the medium are along the direction of wave propagation, sound waves are longitudinal waves.

Question 5.
What is sound and how is it produced?
Answer:
Sound is a form of energy which produces the sensation of hearing. It is produced due to vibrations of different objects, eg. stretched vibrating wires and vibrating drums, etc.

Question 6.
How can two whales in the sea, hundreds of kilometers apart, communicate?
Answer:
Sound travels about 5 times faster in water than in air. Therefore, two whales in the sea, hundreds of kilometers apart can communicate easily.

Question 7.
What is a stethescope? What is the principle on which it works?
Answer:
Stethescope is a medical instrument used for listening to sounds produced in the body. In stethescopes, the sounds reach doctor’s ears by multiple reflections that happen in the connecting tube.

Question 8.
What is an ECG? How does it help in the field of medicine?
Answer:
The electrocardiogram (ECG) is one of the simplest and oldest cardiac investigations available. In ECG, the sound variations produced by heart is converted into electric signals. Thus an ECG is simply a representation of the electrical activity of the heart muscle as it changes with time. Usually it is printed on paper for easy analysis. The sum of this electrical activity, when amplified and recorded for just a few seconds is known as an ECG.

You can Download Samacheer Kalvi 9th Science Book Solutions Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 6 Light

Samacheer Kalvi 9th Science Light Textbook Exercises

I. Choose the correct answer.

Question 1.
A ray of light passes from one medium to another medium. Refraction takes place when angle of incidence is …………..
(a) 0°
(b) 45°
(c) 90°
Answer:
(b) 45°

Question 2.
…………. is used as reflectors in torchlight.
(a) Concave mirror
(b) Plane mirror
(c) Convex mirror
Answer:
(a) Concave mirror

Question 3.
We can create enlarged, virtual images with ………………
(a) Concave mirror
(b) Plane mirror
(c) Convex mirror
Answer:
(a) Concave mirror

Question 4.
When the reflecting surface is curved outwards the mirror formed will be
(a) concave mirror
(b) convex mirror
(c) plane mirror
Answer:
(b) convex mirror

Question 5.
When a beam of white light passes through a prism it gets
(a) reflected
(b) only deviated
(c) deviated and dispersed
Answer:
(a) Reflected

Question 6.
The speed of light is maximum in
(a) vacuum
(b) glass
(c) diamond
Answer:
(a) vacuum

II. True or False – If false give the correct answer.

1. The angle of deviation depends on the refractive index of the glass – True.
2. If a ray of light passes obliquely from one medium to another, it does not suffer any deviation – False.
   Correct Statement: When light travels from one medium to another, it suffers deviation.
3. The convex mirror always produces a virtual, diminished and erect image of the object – True.
4. When an object is at the centre of curvature of concave mirror the image formed will be virtual and erect – False.
   Correct Statement: The image formed is real, inverted and same size of the object.
5. The reason for brilliance of diamonds is total internal reflection of light – True.

III. Fill in the blanks.

1.  In going from a rarer to denser medium, the ray of light bends …………….
2. The mirror used in search light is ………………
3. The angle of deviation of light ray in a prism depends on the angle of ……………..
4. The radius of curvature of a concave mirror whose focal length is 5 cm is …………….
5. Large ………… mirrors are used to concentrate sunlight to produce heat in solar furnaces.

Answer:

1. towards normal
2. concave mirror
3. prism and angle of incident
4. 10 cm
5. concave

IV. Match the following.

1. Ratio of height of image to height of object	(a) Concave Mirror
2. Used in hairpin bends in mountains	(b) Total Internal Reflection
3. Coin inside water appearing slightly raised	(c) Magnification
4. Mirage	(d) convex Mirror
5. Used as Dentist’s mirror	(e) Refraction

Answer:

1. (c)
2. (d)
3. (e)
4. (b)
5. (a)

V. Assertion & Reason.

Mark the correct choice as:
(a) If both assertion and reason are true and reason is the correct explanation.
(b) If both assertion and reason are true and reason is not the correct explanation.
(c) If assertion is true but reason is false.
(d) If assertion is false but reason is true.

Question 1.
Assertion: For observing the traffic at a hairpin bend in mountain paths a plane mirror is
preferred over convex mirror and concave mirror.
Reason : A convex mirror has a much larger field of view than a plane mirror or a concave mirror.
Answer:
(d) If assertion is false but reason is true.

Question 2.
Assertion : Incident ray is directed towards the centre of curvature of spherical mirror.
After reflection it retraces its path.
Reason : Angle of incidence i = Angle of reflection r = 0°.
Answer:
(b) If both assertion and reason are true and reason is not the correct explanation.

VI. Answer very briefly.

Question 1.
According to the cartesian sign convention, which mirror and which lens has a negative focal length?
Answer:
Concave Mirror

Question 2.
Name the mirror(s) that can give (i) an erect and enlarged image, (II) the same sized, inverted image.
Answer:
Concave mirror

Question 3.
If an object is placed at the focus of a concave mirror, where is the image formed?
Answer:
Infinity.

Question 4.
Why does a ray of light bend when it travels from one medium to another?
Answer:
The bending of light rays when they pass obliquely from one medium to another medium is called refraction of light.

Light rays get deviated from their original path while entering from one transparent medium to another medium of different optical density. This deviation (change in direction) in the path of light is due to the change in velocity of light in the different mediums. The velocity of light depends on the nature of the medium in which it travels.

Question 5.
What is speed of light in vacuum?
Answer:
The only medium in which speed of light is equal to that in a vacuum is air. Speed of light in a vacuum is 3 × 10⁸ m/s. Armand Fizeau first measured the speed of light.

Question 6.
Concave mirrors are used by dentists to examine teeth. Why?
Answer:
As a dentist’s head mirror: You would have seen a circular mirror attached to a band tied to the forehead of the dentist/ENT specialist. A parallel beam of light is made to fall on the concave mirror; this mirror focuses the light beam on a small area of the body (such as teeth, throat etc.).

VII. Answer briefly.

Question 1.
(a) Complete the diagram to show how a concave mirror forms the image of the object.
(b) What is the nature of the image?

Solution:
(a)
(b) magnified, real, and inverted.

Question 2.
Pick out the concave and convex mirrors from the following and tabulate them
Answer:
Rear-view mirror, Dentist’s mirror, Torch-light mirror, Mirrors in shopping malls, Make-up mirror.

Concave mirror	Convex mirror
Dentist’s mirror	Rear view mirror
Torch light mirror	Mirrors in shopping malls
Make-up mirror

Question 3.
State the direction of the incident ray which after reflection from a spherical mirror retraces its path. Give reason for your answer.
Answer:
The incident ray is directed towards the centre of curvature
Reason: The ray is normal to the spherical mirror, so ∠ i = o, .’. ∠r = o

Question 4.
What is meant by magnification? Write its expression. What is its sign for real image and virtual image?
Answer:
Magnification produced by a spherical mirror gives how many times the image of an object is magnified with respect to the object size.
It can be defined as the ratio of the height of the image (h_i) to the height of the object (h_o).
Magnification = m = \(\frac{h_{i}}{h_{o}}=\frac{\text { height of the image }}{\text { height of the object }}\)

• for real image it is negative,
• for virtual image it is positive.

Question 5.
Write the spherical mirror formula and explain the meaning of each symbol used in it.
Answer:
Mirror formula:
\(\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\)
Here, f – focal length of a spherical mirror
u – distance of the object from the pole of the mirror
v – distance of image from the pole of the mirror

VIII. Answer in detail.

Question 1.
(a) Draw ray diagrams to show how the image is formed, using a concave mirror when the position of object is

1.  at C
2.  between C and F
3.  between F and P of the mirror.

Answer:
(1) At the centre of curvature C

(2) Between C and F

(3) Between the focus F and the Pole P of the mirror.

(b) Mention the position and nature of image in each case.
Answer:

Position of object	Position of Image	Nature of Image
At the centre of curvature C	AtC	Real and Inverted
Between C and F	Beyond C	Real and inverted
Between F and P	Behind the mirror	Virtual and Erect

Question 2.
Explain with diagrams how refraction of incident light takes place from
(a) rarer to denser medium
(b) denser to rarer medium
(c) normal to the surface separating the two media.
Answer:
(a) rarer to denser medium:
When a ray of light travels from an optically rarer medium to an optically denser medium, it bends towards the normal.

(b) denser to rarer medium:
When a ray of light travels from an optically denser medium to an optically rarer medium it bends away from the normal.

(c) normal to the surface separating the two media:
A ray of light incident normally on a denser medium goes without any deviation.

IX. Numerical Problems.

Question 1.
A concave mirror produces three times magnified real image of an object placed at 7 cm in front of it. Where is the image located? (21 cm in front of the mirror)
Answer:
Given: h_i = 3h_o
u = 7 cm
Solution:

1. m = \(\frac{h_{i}}{h_{O}} \Rightarrow \frac{3 h o}{h_{O}}\) ∴ m = 3.
2. m = – \(\frac{v}{u}\)
   v = – m × u
   = – 3 × 7 cm = – 21 cm.
   Hence, a real, inverted, and the magnified image will be formed at 21 cm in front of the mirror.

Question 2.
Light enters from air into a glass plate having a refractive index 1.5. What is the speed of light in glass? (2 × 10⁸ ms^{– 1})
Given: Refractive index (µ) = 1.5
Speed of light in vacuum (c) = 2 × 10⁸ms^{– 1}
Speed of light in glass (υ) = ?
Solution:

∴ Speed of light in glass = 1.3 × 10⁸ ms< sup>- 1

Question 3.
The speed of light in water is 2.25 × 10⁸ms^{– 1}. If the speed of light in vacuum is 3 × 10⁸ms^{– 1}, calculate the refractive index of water.
Given:
Speed of light in water (υ) = 2.25 × 10⁸ms^{– 1}
Speed of light in vacuum (c) = 3 × 10⁸ms^{– 1}
Solution:
μ = \(\frac{c}{υ}\) ⇒ μ = \(\frac{3 \times 10^{8} \mathrm{ms}^{-1}}{2.25 \times 10^{8} \mathrm{ms}^{-1}}\)
∴ μ = 1.33

X. HOTS.

Question 1.
Light ray emerges from water into air. Draw a ray diagram indicating the change in its path in water.
Answer:

When a ray of light travels from dense medium to rarer medium [from water medium to air medium], light ray moves away from the normal.
∴ Angle of incidence < Angle of refraction.

Question 2.
When a ray of light passes from air into glass, is the angle of refraction greater than or less than the angle of incidence?
Answer:

When a ray of light travels from rare (air) medium to dense [glass] medium, light ray moves towards the normal.
∴ Angle of refraction < Angle of incidence.

Question 3.
What do you conclude about the speed of light in diamond if the refractive index of diamond is 2.41? way from the mirror. Does the image become smaller or larger? What do you observe?
Answer:
µ = 2.41; Ca = 3 × 10⁸ms [Velocity of light]
µ = \(\frac{\text { Speed of light in air }}{\text { Speed of light in diamond }}=\frac{\mathrm{C}_{\mathrm{a}}}{\mathrm{C}_{\mathrm{d}}}\)
C_d = \(\frac{C_{a}}{\mu}=\frac{3 \times 10^{8}}{2.41}\) = 1. 245 × 10⁸ m/s
∴ Speed of light decreases when the light ray travels from air to diamond.

ACTIVITY

Question 1.
Stand before the mirror in your dressing table or the mirror fixed in a steel almirah. Do you see your whole body?
Answer:
To see your entire body in a mirror, the mirror should be atleast half of your height.
Height of the mirror = Your height/2.

Question 2.
Hold a concave mirror in your hand (or place it in a stand). Direct its reflecting surface towards the sun. Direct the light reflected by the mirror onto a sheet of paper held not very far from the mirror. Move the sheet of paper back and forth gradually until you find a bright, sharp spot of light on the paper. Position the mirror and the paper at the same location for few moments. What do you observe? Why does the paper catches fire?
Answer:
The concave mirror focus the sunlight at one particular point. At that particular point, amount of sunlight is converged and heat is trapped at that point. This is because, it bum the paper on which the image is focused.

Question 3.
Take a convex mirror. Hold it in one hand. Hold a pencil close to the mirror in the upright position in the other hand. Observe the image of the pencil in the mirror. Is the image erect or inverted? Is it diminished or enlarged? Move the pencil slowly away from the mirror. Does the image become smaller or larger? What do you observe?
Answer:
When we hold a pencil in the upright position in front of a convex mirror we observe the image of the pencil at the back of the mirror. The image is erect, virtual and smaller in size than the object. As the pencil is moved away from the mirror, the image becomes smaller. When the object is moved away from the mirror, the image would move closer to the focus of the mirror.

Question 4.
Refraction of light at air – water interface
Put a straight pencil into a tank of water or beaker of water at an angle c 45° and look at it from one side and above. How does the pencil look now?
Answer:

The pencil appears to be bent at the surface of water.

Samacheer Kalvi 9th Science Light In Text Problems

Question 1.
Find the size, nature and position of the image formed when an object of size 1 cm is placed at a distance of 15 cm from a concave mirror of focal length 10 cm.
Solution:
Object distance, u = – 15 cm (to the left of mirror)
Image distance, v = ?
Focal length,f = – 10 cm (concave mirror)
Using mirror formula,

Thus, image distance, v = – 30 cm (negative sign indicates that the image is on the left side of the mirror).
∴ Position of image is 30 cm in front of the mirror. Since the image is in front of the mirror, it is real and inverted.
To find the size of the image, we have to calculate the magnification.
m = \(\frac{-v}{u}=\frac{-(-30)}{(-15)}\) = – 2
We know that, m = \(\frac{h_{2}}{h_{1}}\)
Here, height of the object h₁ = 1 cm
– 2 = \(\frac{h_{2}}{1}p.\)
h₂ = – 2 × 1 = – 2 cm
The height of image is 2 cm (negative sign shows that the image is formed below the principal axis).

Question 2.
An object 2 cm high is placed at a distance of 16 cm from a concave mirror which produces a real image 3 cm high. Find the position of the image.
Solution:
Height of object h₁ = 2 cm
Height of real image h₂ = – 3 cm

The position of image is 24 cm in front of the mirror (negative sign indicates that the image is on the left side of the mirror).

Question 3.
A car is fitted with a convex mirror of focal length 20 cm. Another car is 6 m away from the first car. Find the position of the second car as seen in the mirror of the first. What is the size of the image if the second car is 2 m broad and 1.6 m high?
Solution:
Focal length = 20 cm (convex mirror)
Object distance = – 6m = – 600 cm
Image distance v =?

Height of image = \(\frac{1}{31}\) × 160 cm = 5.16 cm

Question 4.
The speed of light in air is 3 × 10⁸ ms^{– 1} and in glass it is 2 × 10⁸ ms^{– 1}. What is the
refractive index of glass?
Solution:
\(_{a} \mu_{g}=\frac{3 \times 10^{8}}{2 \times 10^{8}}=\frac{3}{2}\) = 1.5

Question 5.
Light travels from a rarer medium to a denser medium. The angles of incidence and refraction are respectively 45° and 30°. Calculate the refractive index of the second medium with respect to the first medium.
Solution:
Angle of incidence i = 45° ; Angle of refraction r = 30°
\(_{1} \mu_{2}=\frac{\sin i}{\sin r}=\frac{\sin 45^{\circ}}{\sin 30^{\circ}}=\frac{1 / \sqrt{2}}{1 / 2}=\sqrt{2}\) = 1.414

You can Download Samacheer Kalvi 9th Science Book Solutions Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 5 Magnetism and Electromagnetism

Samacheer Kalvi 9th Science Magnetism and Electromagnetism Textbook Exercises

I. Choose the correct answer.

Question 1.
Which of the following converts electrical energy into mechanical energy?
(a) motor
(b) battery
(c) generator
(d) switch
Answer:
(a) motor

Question 2.
The part of the AC generator that passes the current from the armature coil to the external circuit is
(a) field magnet
(b) split rings
(c) slip rings
(d) brushes
Answer:
(d) brushes

Question 3.
Transformer works on
(a) AC only
(b) DC only
(c) both AC and DC
(d) AC nor effectively than DC
Answer:
(a) AC only

Question 4.
The unit of magnetic flux density is
(a) Weber
(b) weber/meter
(c) weber/meter²
(d) weber.meter²
Answer:
weber/meter²

II. Fill in the blanks.

1. The SI Unit of magnetic field induction is ……………………..
2. Devices which is used to convert high alternating current to low alternating current is …………………..
3. An electric motor converts …………………..
4. A device for producing electric current is ……………………..

Answer:

1. Tesla
2. Step down transformer
3. Electrical energy into mechanical energy
4. Generator

III. Match the following.

Column – I	Column – II
1. Magnetic material	(a) Oersted
2. Non-magnetic material	(b) iron
3. Current and magnetism	(c) induction
4. Electromagnetic induction	(d) wood
5. Electric generator	(e) Faraday

Answer:

1. (b) iron
2. (d) wood
3. (a) Oersted
4. (e) Faraday
5. (c) induction

IV. True or False.

1. A generator converts mechanical energy into electrical energy – True

2. Magnetic field lines always repel each other and do not intersect – True

3. Fleming’s Left-hand rule is also known as Dynamo rule – True

4. The speed of rotation of an electric motor can be increased by decreasing the area of the coil – False
Correct Statement: The speed of rotation of the coil can be increased by increasing the area of the coil.

5. A transformer can step up direct current – False
Correct Statement: A transformer can step up the alternating current.

6. In a step-down transformer, the number of turns in the primary coil is greater than that of the number of turns in the secondary coil – True

V. Answer in brief.

Question 1.
State Fleming’s Left Hand Rule.
Answer:
The law states that while stretching the three fingers of the left hand in a perpendicular manner with each other if the direction of the current is denoted by the middle finger of the left hand and the second finger is for the direction of the magnetic field then the thumb of the left hand denotes the direction of the force or movement of the conductor.

Question 2.
Define magnetic flux density.
Answer:
The number of magnetic field lines crossing unit area kept normal to the direction of field lines is called magnetic flux density. Its unit is Wb/m²

Question 3.
List the main parts of an electric motor.
Answer:
Main parts of an electric motor

• Field magnet.
• Armature (Rectangular coil)
• Split ring (Commutator)
• Brushes
• Battery

Question 4.
Draw and label the diagram of an AC generator.
Answer:

Question 5.
State the advantages of AC over DC.
Answer:

• The cost of generation of AC is less than the cost of generation of DC.
• AC can be easily converted into D.C.
• Only alternating voltage can be stepped up or stepped down by using a transformer.
• AC can be transmitted to distant places without much loss of electric power than DC.

Question 6.
Differentiate step up and step down transformer.
Answer:

Step-up transformer	Step down transformer
The transformer used to change a low alternative voltage to a high alternating voltage is called a step-up transformer, i.e. (Vs>Vp).	The transformer used to change a high alternating voltage to a low alternating voltage is called a step-down transformer (Vs <Vp).
In a step up transformer, the number of turns in the secondary coil is more than the number of turns in the primary coil (Ns > Np)	In a step-down transformer, the number of turns in the secondary coils are less than the number of turns in the primary coil (Ns < Np)

Question 7.
A portable radio has a built-in transformer so that it can work from the mains instead of batteries. Is this a step up or step down transformer?
Answer:
It is a step-down transformer. So that rectified DC voltage is equal to battery voltage, hence it can work on mains as well as on battery.

Question 8.
State Faraday’s laws of electromagnetic induction.
Answer:
Whenever there is a change in the magnetic flux linked with a closed-circuit an emf is produced and the amount of emf induced varies directly as the rate at which the flux changes. This emf is known as induced emf and the phenomenon of producing an induced emf due to a change in the magnetic flux linked with a closed circuit is known as electromagnetic induction.

VI. Answer in detail.

Question 1.
Explain the principle, construction, and working of a DC motor.
Answer:
A motor is an electrical machine which converts electrical energy into mechanical energy. The principle of working of a DC motor according to Faraday’s laws of electromagnetic induction is that “whenever a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force”. The various parts of a DC motor are; Permanent magnets on both sides of a coil which consists of carbon brush and commutator as shown in

Working of electric motor is primarily dependent upon the interaction between magnetic field and current. The direction of this force is given by Fleming’s left hand rule and it’s magnitude is given by F = BIL. Where, B = magnetic flux density, I = current and L = length of the conductor within the magnetic field.

Question 2.
Explain two types of transformer.
Answer:
Transformer is a device used for converting low voltage into high voltage and high voltage into low voltage. It works on the principle of electromagnetic induction. It consists of primary and secondary coil insulated from each other. Depending upon the number of turns in the primary and secondary coils, the two types of transformers are; step-up or step-down transformers.

Step-up transformer:
The transformer used to change a low alternative voltage to a high alternating voltage is called a step-up transformer, ie (Vs > Vp). In a step-up transformer, the number of turns in the secondary coil is more than the number of turns in the primary coil (Ns > Np).

Step down transformer:
The transformer used to change a high alternating voltage to a low alternating voltage is called a step-down transformer (Vs < Vp). In a step-down transformer, the number of turns in the secondary coils is less than the number of turns in the primary coil (Ns < Np).
The formulae pertaining to the transformers are given in the following equations.

• • The number of primary turns N_p / The number of secondary turns N_s = The primary voltage V_p/ The secondary voltage V_s
  • The number of secondary turns N_s / The number of primary turns N_p – The primary current I_p/ The secondary current I_s

Question 3.
Draw a neat diagram of an AC generator and explain its working.
Answer:
An alternating current (AC) generator, consists of a rotating rectangular coil ABCD called armature placed between the two poles of a permanent magnet. The two ends of this coil are connected to the two slip rings S₁ and S₂. The inner sides of these rings are insulated. Two conducting stationary brushes B₁ and B₂ are kept separately on the rings S₁ and S₂ respectively. The two rings S₁ and S₂ are internally attached to an axle. The axle may be mechanically rotated from outside to rotate the coil inside the magnetic field. Outer ends of the two brushes are connected to the external circuit.

When the coil is rotated, the magnetic flux linked with the coil changes. This change in magnetic flux will lead to the generation of induced current. The direction of the induced current, as given by Fleming’s Right Fland Rule, is along ABCD in the coil, and in the outer circuit, it flows from B₂ to B₁. During the second half of rotation, the direction of current is along DCBA in the coil, and in the outer circuit it flows from B₁ to B₇. As the rotation of the coil continues, the induced current in the external circuit is changing its direction for every half a rotation of the coil.

ACTIVITY

Question 1.
Put a magnet on a table and place some paper clips nearby. If you push the magnet slowly towards the paper clips, there will be a point at which the paper clips jump across and stick to the magnet. What do you understand from this?
Answer:

The invisible magnetic field that surrounds the magnet acts at a particular distance. This magnetic field attracts the paper clip which is made of steel.

Samacheer Kalvi 9th Science Magnetism and Electromagnetism In-Text Problems

Question 1.
A conductor of length 50 cm carrying a current of 5 A is placed perpendicular to a magnetic field of induction 2 × 10^{– 3} T. Find the force on the conductor.
Solution:
Force on the conductor = ILB
= 5 × 50 × 10^{– 2} × 2 × 10^{– 3}
= – 5 × 10^{– 3} N

Question 2.
A current-carrying conductor of a certain length, kept perpendicular to the magnetic field experiences a force F. What will be the force if the current is increased four times, the length is halved and the magnetic field is tripled?
Solution:
F = ILB = (4I) × ( L / 2) × (3 B) = 6 F
Therefore, the force increases six times.

Question 3.
The primary coil of a transformer has 800 turns and the secondary coil has 8 turns. It is connected to a 220 V ac supply. What will be the output voltage?
Solution:
In a transformer, E_s / E_p = N_s / N_p
E_s = N_s / N_p × E_p
= \(\frac { 8 }{ 800 }\) × 220 = \(\frac { 220 }{ 100 }\) = 2.2 volt

Samacheer Kalvi 9th Science Magnetism and Electromagnetism Additional Questions

I. Short Answers Questions.

Question 1.
What are natural magnets?
Answer:
Natural magnets exist in nature and can be found in rocks and sandy deposits in various parts of the world.

Question 2.
How can the speed of rotation of a coil be increased? Write at least three methods.
Answer:
The speed of rotation of a coil can be increased by;

• increasing the strength of the Current in the coil
• increasing the area of the coil
• increasing the strength of the magnetic field.

Question 3.
What is the connection between electricity and magnetism?
Answer:
Electricity and magnetism are closely related to each other. The current flowing through the wire produces a circular magnetic field outside the wire. The direction of this magnetic field depends on the electric current.

Similarly, a changing magnetic field produces an electric current in a wire or conductor. The relationship between electricity arid magnetism is called electromagnetism.

Question 4.
What are the factors that determine the strength of the magnet?
Answer:
The strength of the magnetic field at a point due to current-carrying wire depends on:

• the current in the wire
• distance of the point from the wire
• the orientation of the point from the wire and
• the magnetic nature of the medium.

Question 5.
Name some equipment that uses electromagnetism for functioning.
Answer:
Many of the medical equipment such as scanners, x-ray equipment, and other equipment also use the principle of electromagnetism for their functioning.

Question 6.
Explain why the ozone layer is not affected by the solar wind.
Answer:
Magnetic field can penetrate through all kinds of materials. The Earth produces its own magnetic field, which shields the earht’s ozone layer from the solar wind.

Question 7.
Write the properties of magnetic lines of force.

• Magnetic lines of force are closed continuous curves, extending through the body of the magnet.
• Magnetic lines of force start from the North Pole and end at the South Pole.
• Magnetic lines of force never intersect.
• They will be maximum at the poles than at the equator.
• The tangent drawn at any point on the curved line gives the direction of the magnetic field.

II. Long Answers Questions.

Question 1.
What do you know about Michael Faraday?
Answer:
Michael Faraday discovered that a current-carrying conductor also gets deflected when it is placed in a magnetic field. Michael Faraday was a British Scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism, and electrolysis. Although Faraday received little formal education, he was one of the most influential scientists in history. Faraday was an excellent experimentalist who conveyed his ideas in clear and simple language.

The SI unit of capacitance is named in his honour: the farad. Albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell. Faraday is one of the greatest scientific discoverers of all time.

Question 2.
Explain in detail the application of electromagnets.
Answer:
Applications of electromagnets – Electromagnetism has caused a great impact on various fields such as medicine, industries, space, etc. In our day to day life, it finds application in;
(a) Speakers – In a speaker, the electromagnet is placed in front of a permanent magnet. The permanent magnet is fixed whereas the electromagnet is mobile. As pulses of electricity pass through the coil of the electromagnet, the direction of its magnetic field rapidly changes. This causes it to get attached to and repelled from the permanent magnet, thereby causing vibration. The electromagnet is attached to a cone made of plastic or paper which amplifies the sound and the waves reaching our ears.

(b) Maglev – Magnetic levitation trains are suspended with no support other than magnetic fields. In maglev trains, two sets of magnets are used. One set to repel and push the train up off the track, and another to move the floating train ahead at a great speed without friction. The train travels along a guideway of magnets which controls the tram’s stability and speed using the basic principles of magnets.

(c) MRI Scanner – Magnetic resonance imaging is a procedure using sophisticated instruments that work on the principle of electromagnetism that can scan minute details of the human body. Other medical equipment such as X-rays etc., also use this principle for their functioning.