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Samacheer Kalvi 9th Science Solutions Chapter 5 Magnetism and Electromagnetism

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.

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

Answer:

Tesla
Step down transformer
Electrical energy into mechanical energy
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:

(b) iron
(d) wood
(a) Oersted
(e) Faraday
(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. (V_s>V_p).	The transformer used to change a high alternating voltage to a low alternating voltage is called a step-down transformer (V_s <V_p).
In a step up transformer, the number of turns in the secondary coil is more than the number of turns in the primary coil (N_s > N_p)	In a step-down transformer, the number of turns in the secondary coils are less than the number of turns in the primary coil (N_s < N_p)

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.

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Samacheer Kalvi 7th Maths Solutions Term 2 Chapter 2 Measurements Ex 2.2

Tamilnadu Samacheer Kalvi 7th Maths Solutions Term 2 Chapter 2 Measurements Ex 2.2

Question 1.
Find the area of the dining table whose diameter is 105 cm.
Solution:
Diameter of the dinig table (d) = 105 cm
∴ Radius r = \(\frac { d }{ 2 } \) = \(\frac { 105 }{ 2 } \) cm
Area of the circle = π r² = \(\frac { 22 }{ 7 } \) × \(\frac { 105 }{ 2 } \) × \(\frac { 105 }{ 2 } \) = 8662.5 sq.cm
Area of the dinning table = 8662.5 cm²

Question 2.
Calculate the area of the shotput ring whose diameter is 2.135 m.
Solution:
Radius of the shotput ring r = \(\frac { d }{ 2 } \) = \(\frac { 2.135 }{ 2 } \) m
Area of the circle = π r²
= \(\frac { 22 }{ 7 } \) × \(\frac { 2.135 }{ 2 } \) × \(\frac { 2.135 }{ 2 } \)
= \(\frac { 25.07 }{ 7 } \) = 3.581 m²
∴ Area of the shotput ring = 3.581 m²

Question 3.
A sprinkler placed at the centre of a flower garden sprays water covering a circular area. If the area watered is 1386 cm2, find its radius and diameter.
Solution:
Area of the Circle = π r² sq.units
Area of the circular portion watered = 1386 cm²
π r² = 1386
\(\frac { 22 }{ 7 } \) × r² = 1386
r² = 1386 × \(\frac { 7 }{ 22 } \) = 63 × 7 = 9 × 7 × 7
r² = 3² × 7²
r = 3 × 7
Radius (r) = 21 cm
Diameter (d) = 2 r = 2 × 21 cm
Diameter (d) = 42 cm

Question 4.
The circumference of a circular park is 352 m. Find the area of the park.
Solution:
Circumference of a Circle = 2 π r units
Given circumference of a circular park = 352 m
2 π r = 352
2 × \(\frac { 22 }{ 7 } \) × r = 352
r = 352 × \(\frac { 7 }{ 22 } \) × \(\frac { 1 }{ 2 } \) = 56 m
Area of the park = π r² = \(\frac { 22 }{ 7 } \) × 56 × 56 sq.units
= 22 × 8 × 56 = 9856 m²
∴ Area of the Circular park = 9856 m²

Question 5.
In a grass land, a sheep is tethered by a rope of length 4.9 m. Find the maximum area that the sheep can graze.

Solution:
Length of the rope = 4.9 m
Area that the sheep can graze = Area of circle with radius 4.9m
Area of the circle = π r² sq.units
= \(\frac { 22 }{ 7 } \) × 4.9 × 4.9 = 22 × 0.7 × 4.9 = 75.46
∴ Area that the sheep can graze = 75.46 m²

Question 6.
Find the length of the rope by which a bull must be tethered in order that it may be able to graze an area of 2464 m².
Solution:
If the bull is tethered by a rope then the area it can graze is a circular area of radius
= length of the rope
Area of the circle = 2464 m²
π r² = 2464 m²
\(\frac { 22 }{ 7 } \) × r² = 2464
r² = 2464 × \(\frac { 7 }{ 22 } \) = 122 × 7 = 16 × 7 × 7
r² = 42 × 72
r = 4 × 7 = 28 m
length of the rope r = 28 m

Question 7.
Lalitha wants to buy a round carpet of radius is 63 cm for her hall. Find the area that will be covered by the carpet.
Solution:
Radius of the round carpet = 63 cm
Area covered by the round carpet = πr² sq units
A = \(\frac { 22 }{ 7 } \) × 63 × 63 = 22 × 9 × 63 = 12474 cm²
Area covered by the round carpet = 12,474 cm²

Question 8.
Thenmozhi wants to level her circular flower garden whose diameter is 49 m at the rate of ₹150 per m² Find the cost of levelling.
Solution:
Diamter of the circular garden d = 49 m
Radius r = \(\frac { d }{ 2 } \) = \(\frac { 49 }{ 2 } \) m
Area of the circular garden = πr² sq units
= \(\frac { 22 }{ 7 } \) × \(\frac { 49 }{ 2 } \) × \(\frac { 49 }{ 2 } \) m² = 1,886.5 m²
Cost of levelling a m² area = ₹ 150
∴ Cost of levelling 1886.5 m² = ₹ 150 × 1886.5 = ₹ 2,82,975
Cost of levelling the flower garden = ₹ 2,82,975

Question 9.
The floor of the circular swimming pool whose radius is 7 m has to be cemented at the rate of ₹ 18 per m². Find the total cost of cementing the floor.
Solution:
Radius of the circular swimming pool r = 7 m
Area of the circular swimming pool A = πr² sq. units
= \(\frac { 22 }{ 7 } \) × 7 × 7 m² = 154 m²
Cost of cementing a m² floor = ₹ 18.
Cost of cementing 154 m² floor = ₹ 18 × 154 = ₹ 2,772

Objective Type Questions

Question 10.
The formula used to find the area of the circle is
(i) 47πr²
(ii) πr²
(iii) 2πr²
(iv) πr² + 2r
Answer:
(ii) πr²

Question 11.
The ratio of the area of a circle to the area of its semicircle is
(i) 2 : 1
(ii) 1 : 2
(iii) 4 : 1
(iv) 1 : 4
Answer:
(i) 2 : 1

Question 12.
Area of circle of radius ‘n’ units is
(i) 2πr^p sq.units
(ii) πm² sq.units
(iii) πr² sq.units
(iv) πn² sq.units
Answer:
(iv) πn² sq.units

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Samacheer Kalvi 10th English Grammar Link Words

Tamilnadu Samacheer Kalvi 10th English Grammar Link Words

Linking words and phrases in English (also called ‘connective’ or ‘transition’ words) are used to combine two clauses or sentences presenting contrast, comparison, condition, supposition, purpose, etc. They enable us to establish clear connections between ideas.

Complete the sentence with an appropriate link word.
1. Promise me that you will phone me …………………………. you get to the railway station.
2. “I’ll take some money with me just …………………………. I see something I want to buy.”
3. Jenni promised to look after Hari’s cat …………………………. she was on holiday.
4. It is a small house and requires a lot of repairs …………………………., it is a long way from the center.
5. He was let off …………………………. he would not repeat the offense.
6. He wore a coat …………………………. he might not catch cold.
7. It has been raining continuously …………………………. last week.
8. She was …………………………. unable to attend the meeting.
9. He was so tired …………………………. he had stayed up late to watch the football match.
10. …………………………. you stop eating so much chocolate you won’t be able to fit into your favorite dress.
11. I have to complete this assignment …………………………. the end of the day.
12. I saw him go into the office and ten minutes …………………………. he came out looking very pale.
13. …………………………. having a swim we lay in the sun, watching the boats in the distance.
14. He could beat his father at chess …………………………. he was only 8.
15. I like holidays by the sea …………………………. my husband prefers to go to the mountains.
16. …………………………. the high risk involved, many scientists chase tornadoes so they can study them more closely.
17. …………………………. television can be educational, I think it’s better to read a book.
18. …………………………. the rain and the high winds, they never went camping.
19. You are not eligible for a subsidized bus pass …………………………. you are a full-time student.
20. He was an absolute failure in medical school, so he decided to try law ………………………….
Answer:
1. as soon as
2. in case
3. while
4. Moreover
5. on condition that
6. in order that
7. since
8. therefore
9. because
10. Unless
11. by
12. later
13. After
14. although
15. whereas
16. Despite
17. Even though
18. Due to
19. unless
20. instead

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Samacheer Kalvi 10th English Grammar Translation

Tamilnadu Samacheer Kalvi 10th English Grammar Translation

A. TAMIL TO ENGLISH
1. You see a notice at the bus terminus. A North Indian, who cannot read Tamil, needs your help in understanding the notice. Give him the message in English.

Answer:
Danger: The smoke left by a smoker could cause cancer in a non-smoker. Avoiding smoking in public places is good for others. Abstaining from the habit of smoking completely is good for all.

2. A foreigner is driving a car. He comes to a river which has two bridges. He sees before him a board in Tamil. As he does not know Tamil, help him to understand the instructions through your translation.

Answer:
Warning: This bridge is under repair. Four wheelers and heavy vehicles should pass only through the new bridge.

3. A co-passenger on the bus you travel in has slipped and sprained his ankle. He wishes to go to a hospital nearby. Someone gives him the instructions in Tamil. As he is new to Tamil Nadu, as he does not understand the language. Translate the instructions into English to help him.

Answer:
From the bus stop, go straight in the Mahatma Gandhi Road. There is a big post of fice to your right. Cross the road across. Enter the road near Indian Bank. To your left you would find Malar Hospital in the second building.

4. You see a notice in the railway station. A North Indian who cannot read tamil, needs your help in understanding the notice. Give him the message in English.

Answer:
Do not accept food from unfamiliar persons. Do not board or alight from running train. Do not carry easily inflammable articles in train.

5. Your neighbour wants to go to SBI, ATM. As your neighbour does not know Tamil, translate the instruction into English.

Answer:
Those who travel in Electric trains must renew their passes every month. Apart from this, they can also get their passes for a quarter, six months or a year after paying the required money for it. Whenever Ticket Examiner asks for Ticket, they must show the train pass.

B. English To Tamil
6. “An old farmer from a village has come to a city public school to obtain an application for his grandson. He is unable to read the instructions which are in English as he doesn’t know the language. Translate the instructions into Tamil to help the farmer: Parents wishing to admit their wards in this school can obtain the application forms by paying ₹100 in cash at Counter No. : 1. If you require the application form to be sent by post, kindly submit a Demand Draft (D.D) for ₹ 100 payable to “The Principal, Orion Public School, Chennai – 14”. Enclose the D.D. with a requisition letter containing the address to which the application form should be sent. Submit the letter and D.D. at Counter No. : 2.
Answer:

7. Scientists say that millet cultivation needs to be further encouraged to adapt to global warming that leads to losses in crop yields. There is a marked improvement in our health and stamina after we reverted to a millet diet from rice a few years back.

8. The flora and fauna of our country are in a great threat due to fast development of technology. Pollution of land, air and water and radio active waste has led to lesser availability of sources of drinking water.

9. Three wild elephants, including two pregnant females, were killed by a speeding train in Assam early on Monday, the official said.

10. “Charity begins at home”, is the famous phrase which completely suits to those people who have forgotten the real preferences in their life like family, close relatives, society, community or their own country. They just help or donate money to others while their family members need them first; in fact completely depended on them.

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Samacheer Kalvi 10th English Vocabulary Affixes (Prefix & Suffix)

Tamilnadu Samacheer Kalvi 10th English Vocabulary Affixes (Prefix & Suffix)

Question 1.
Form a new word by adding a suitable prefix to the root word “vision”.
(a) in ______ (b) un ______ (c) dis ______ (d) en ______
Answer:
(d) envision

Question 2.
Form a new word by adding a prefix to the root word “noble”.
(a) in ______ (b) ig ______ (c) dis ______ (d) mis ______
Answer:
(b) ignoble

Question 3.
Form a new word by adding a suitable prefix to the root word “compass”.
(a) in ______ (b) un ______ (c) en ______ (d) mis ______
Answer:
(c) encompass

Question 4.
Form a new word by adding a suitable suffix to the root word “miser”.
(a) ______al (b) ______ic (c) ______ly (d) ______ness
Answer:
(c) miserly

Question 5.
Form a new word by adding a suitable suffix to the root word “music”.
(a) ______s (b) ______ian (c) ______ir (d) ______ion
Answer:
(b) musician

Question 6.
Form a new word by adding a suitable suffix to the root word “announce”.
(a) ______al (b) ______ic (c) ______r (d) ______ment
Answer:
(d) announcement

Question 7.
Form a new word by adding a suitable suffix to the root word ‘secure’.
(a) ______ity (6) ______ic (c) ______ile (d) ______ion
Answer:
(a) security

Question 8.
Form a new word by adding a suitable suffix to the root word “bright”.
(a) ______al (b) ______ic (c) ______ness (d) ______ion
Answer:
(c) brightness

Question 9.
Form a new word by adding a suitable suffix to the root word “colour”.
(a) ______al (b) ______ic (c) ______ile (d) ______ful
Answer:
(d) colourful

Question 10.
Form a new word by adding a suitable suffix to the root word “human”.
(a) ______al (b) ______ity (c) ______ile (d) ______ion
Answer:
(b) humanity

Question 11.
Form a new word by adding a suitable prefix to the root word “secure”.
(a) in ______ (b) un ______ (c) dis ______ (d) mis ______
Answer:
(a) insecure

Question 12.
Form a new word by adding a prefix to the root word “fair”.
(a) in______ (b) un______ (c) re______ (d) mis______
Answer:
(b) unfair

Question 13.
Form a new word by adding a suitable prefix to the root word “standard”.
(a) in______ (b) un______ (c) dis______ (d) sub______
Answer:
(d) substandard

Question 14.
Form a new word by adding a suitable prefix to the root word “violet”.
(a) ultra______ (b) un______ (c) dis______ (d) mis______
Answer:
(a) ultraviolet

Question 15.
Form a new word by adding a suitable prefix to the root word “power”.
(a) in______ (b) em______ (c) dis______ (d) mis______
Answer:
(b) empower

Question 16.
Form a new word by adding a suitable prefix to the root word “lock”.
(a) in______ (b) un______ (c) dis______ (d) inter______
Answer:
(d) interlock

Question 17.
Form a new word by adding a suitable suffix to the root word “need”.
(a) ______al (b) ______y (c) ______ile (d) ______ion
Answer:
(b) needy

Question 18.
Form a new word by adding a suitable suffix to the root word “danger”.
(a) ______ous (b) ______ic (c) ______ile (d) ______ion
Answer:
(a) dangerous

Question 19.
Form a new word by adding a suitable suffix to the root word “narrate”.
(a) ______al (b) ______ive (c) ______ile (d) ______ion
Answer:
(b) narrative

Question 20.
form a new word by adding a suitable suffix to the root word “kind”.
(a) ______al (b) ______ic (c) ______ile (d) ______ness
Answer:
(d) kindness

Question 21.
Form a new word by adding a suitable prefix to the root word “lap”.
(a) in______ (b) un______ (c) over______ (d) mis______
Answer:
(c) overlap

Question 22.
Form a new word by adding a prefix to the root word “visible”.
(a) in______ (b) un______ (c) dis______ (d) mis______
Answer:
(a) invisible

Question 23.
Form a new word by adding a suitable prefix to the root word “national”.
(a) in______ (b) ir______ (c) multi______ (d) mis______
Answer:
(c) multinational

Question 24.
Form a new word by adding a suitable suffix to the root word “harm”.
(a) ______al (b) ______ic (c) ______ile (d) ______ful
Answer:
(d) harmful

Question 25.
Form a new word by adding a suitable suffix to the root word “neighbour”.
(a) ______al (b) ______ic (c) ______hood (d) ______ion
Answer:
(c) neighbourhood

Question 26.
Form a new word by adding a suitable suffix to the root word “exception”.
(a) ______al (b) ______ic (c) ______ile (d) ______ion
Answer:
(a) exceptional

Question 27.
Form a new word by adding a suitable suffix to the root word ‘national’.
Answer:
(a) ______al (b) ______ic (c) ______ity (d) ______ion
Answer:
(c) nationality

Question 28.
Form a new word by adding a suitable suffix to the root word “champion”.
(a) ______al (b) ______ship (c) ______ile (d) ______ion
Answer:
(b) championship

Question 29.
Form a new word by adding a suitable suffix to the root word “wilder”.
(a) ______al (b) ______ic (c) ______ness (d) ______ion
Answer:
(c) wilderness

Question 30.
Form a new word by adding a suitable suffix to the root word “tradition”.
(a) ______al (b) ______ic (c) ______ile (d) ______ion
Answer:
(a) traditional

Samacheer Kalvi 10th English Vocabulary Affixes (Prefix & Suffix) Read More »

Samacheer Kalvi 7th Maths Solutions Term 2 Chapter 2 Measurements Ex 2.1

Tamilnadu Samacheer Kalvi 7th Maths Solutions Term 2 Chapter 2 Measurements Ex 2.1

Question 1.
Find the missing values in the following table for the circles with radius (r), diameter (d) and Circumference (C).

Solution:
(i) Given radius r = 15cm
∴ diameter d = 2 × 15 = 30 cm
Circumference C = π d units
= \(\frac { 22 }{ 7 } \) × 30 = \(\frac { 660 }{ 7 } \) = 94.28 cm

(ii) Given circumference C = 1760 cm
2πr = 1760
2 × \(\frac { 22 }{ 7 } \) × r = 1760
r = \(\frac{1760 \times 7}{2 \times 22}\) = \(\frac{160 \times 7}{2 \times 2}\) = 40 × 7 = 280 cm
diameter = 2 × r
= 2 × 280 = 560 cm

(iii) diameter d = 24m
radius r = \(\frac { d }{ 2 } \) = \(\frac { 24 }{ 2 } \) = 12 m
Circumference C = 2 π r units
= 2 × \(\frac { 22 }{ 7 } \) × 12 = \(\frac { 528 }{ 7 } \) = 75.4 m

Tabulating the results

Question 2.
Diameters of different circles are given below. Find their circumference (Take π = \(\frac { 22 }{ 7 } \) )
(i) d = 70cm
(ii) d = 56m
(iii) d = 28mm
Solution:
(i) Diameter d = 70 cm
Circumference C = π d units = \(\frac { 22 }{ 7 } \) × 70 = 22 × 10 = 220 cm

(ii) Diameter d = 56 m
Circumference = π d units
= \(\frac { 22 }{ 7 } \) × 56 = 22 × 8 = 176 m

(iii) Diameter d = 28 mm
Circumference C = π d units = \(\frac { 22 }{ 7 } \) × 28 = 22 × 4 = 88 mm

Question 3.
Find the circumference of the circles whose radii are given below.
(i) 49 cm
(ii) 91 mm
Solution:
Radius r = 49 cm
Circumference C = 2 π r units = 2 × \(\frac { 22 }{ 7 } \) × 49 = 2 × 22 × 7
= 44 × 7 = 308 cm

(ii) Radius r = 91 mm
Circumference C = 2 π r units
= 2 × \(\frac { 22 }{ 7 } \) × 91 = 2 × 22 × 13 = 44 × 13 = 572 mm

Question 4.
The diameter of a circular well is 4.2 m. What is its circumference?
Solution:
Given the diameter d = 4.2 m
Circumference C = π d units = \(\frac { 22 }{ 7 } \) × 4.2 m = 22 × 0.6 = 13.2 m

Question 5.
The diameter of the bullock cart wheel is 1.4 m. Find the distance covered by it in 150 rotations?
Solution:
Diameter of the bullock cart wheel d= 1.4 m
Distance covered in 1 rotation = Its circumference
= π d units = \(\frac { 22 }{ 7 } \) × 1 .4 m = 22 × 0.2 = 4.4 m
Distance covered in one rotation = 4.4 m
Distance covered in 150 rotations = 4.4 × 150 = 660.0
Distance covered in 150 rotations = 660 m

Question 6.
A ground is in the form of a circle whose diameter is 350 m. An athlete makes 4 revolutions. Find the distance covered by the athlete.
Solution:
Diameter of the ground d = 350 m
Distance covered in 1 revolution = Circumference of the circle
= π d units = \(\frac { 22 }{ 7 } \) × 350 m = 22 × 50 = 1100 m
Distance covered in 1 rotation = 1100 m
Distance covered in 4 revolutions = 1100 × 4 = 4400 m

Question 7.
A wire of length 1320 cm is made into circular frames of radius 7 cm each. How many frames can be made?
Solution:
Length of the wire = 1320 cm
Radius of each circular frame = 7cm
Circumference of the frame 2 π r units = 2 × \(\frac { 22 }{ 7 } \) × 7 cm = 2 × 22 = 44 cm

30 frames can be made.

Question 8.
A Rose garden is in the form of circle of radius 63 m. The gardener wants to fence it at the rate of ₹ 150 per metre. Find the cost of fencing?
Solution:
Radius of the garden r = 63 m
Circumference of the garden = 2 π r units = 2 × \(\frac { 22 }{ 7 } \) × 63 m = 2 × 22 × 9 = 396 m
Cost of fencing 1 meter = ₹ 150
Cost of fencing 396 meter = ₹ 150 × 396 = ₹ 59,400
∴ Cost of fencing the garden = ₹ 59,400

Objective Type Questions

Question 9.
Formula used to find the circumference of a circle is
(i) 2πr units
(ii) πr² + 2r units
(iii) πr² sq. units
(iv) πr³ cu. units
Answer:
(i) 2πr units

Question 10.
In the formula, C = 2πr, ‘r’ refers to
(i) circumference
(ii) area
(iii) rotation
(iv) radius
Answer:
(iv) radius

Question 11.
If the circumference of a circle is 82π, then the value of ‘r’ is
(i) 41cm
(ii) 82 cm
(iii) 21cm
(iv) 20 cm
Answer:
(i) 41cm

Question 12.
Circumference of a circle is always
(i) three times of its diameter
(ii) more than three times of its diameter
(iii) less than three times of its diameter
(iv) three times of its radius
Answer:
(ii) more than three times of its diameter

Samacheer Kalvi 7th Maths Solutions Term 2 Chapter 2 Measurements Ex 2.1 Read More »