Explore NCERT Solutions

Chapter Review:

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• Lightning is caused by the accumulation of charges in the clouds.
• Lightning is a natural phenomenon which occurs in the sky h clouds sparkwit.
• This is a device by which it is identified of charge on an object is carrying or not. This device is known as electroscope.

• The process of transferring of charge from a charged object to the earth is called earthing.

• When a plastic comb is rubbed with dry hair, it acquires a small charge. These objects are called charged objects.

• The electrical charges produced by rubbing are called static charges.

• There are two kinds of charges — positive charge and negative charge.

• Like charges repel and unlike charges attract each other.

• Negative and positive charges meet, producing streaks of bright light and sound. The process is called an electric discharge.

• The disturbance deep down inside the uppermost layer of the earth called the crust.

• The outermost layer of the earth is not in one piece. It is fragmented. Each fragment is called a plate.

• The plates are the weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones.

• The power of an earthquake is expressed in terms of a magnitude on a scale called Richter scale.

• The tremors produce waves on the surface of the earth. These are called seismic waves. The waves are recorded by an instrument called the seismograph.

• Earthquake is caused by a disturbance deep inside the earth’s crust.

Exercise

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1. Which of the following cannot be charged easily by friction?

(a) A plastic scale

(b) A copper rod

(c) An inflated balloon

(d) A woollen cloth.

Answer:

(b) A copper rod.

2. When a glass rod is rubbed with a piece of silk cloth the rod

(a) and the cloth both acquire positive charge.

(b) becomes positively charged while the cloth has a negative charge.

(c) and the cloth both acquire negative charge.

(d) becomes negatively charged while the cloth has a positive charge.

Answer:

(b) becomes positively charged while the cloth has a negative charge.

3. Write T against true and F against false in the following statements:

(a) Like charges attract each other (T/F)

(b) A charged glass rod attract a charged plastic straw (T/F)

(c) Lightning conductor cannot protect a building from lightning (T/F)

(d) Earthquakes can be predicted in advance (T/F)

Answer:

(a)-f (b)-t (c)-f (d)-f

4. Sometime, a crackling sound is heard while taking off sweater during winters. Explain.

Answer:

A crackling sound is heard because when the sweater is rubbed while taking it, off, it acuquires a small charge.

5. Explain why a charged body loses its charge if we touch it with our hand.

Answer:

Our body is a conductor of electricity. When we touch a charged body loses charge to the earth through our body.

6. Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?

Answer:

The destructive energy of an earthquakq is measured on a scale called Richter scale. 

An earthquake that meausure 3 on the Richter scale will be recorded by seismograph However, it is not likely to cause much damage.

7. Suggest three measures to protect ourselves from lightning.

Answer:

(i) We should rush to a safer place like house or building.

8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

Answer:

A charged ballon is replled by another ballon beecause both have the same charge. And we know similar charges repel each oother.

Butt a charged ballon attracts an uncharged ballon and lose itts own charge too the other ballon. 

9. Describe with the help of a diagram an instrument which can be used to detect a charged body.

10. List three states in India where earthquakes are more likely to strike.

Answer:

The states that fall in seismic zones are more earthquake-prone. Jammu and Kashmir, Himachal Pradesh, and Gujrat are a few such states.

 

Exercise

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1. Which of the following cannot be charged easily by friction?

(a) A plastic scale

(b) A copper rod

(c) An inflated balloon

(d) A woollen cloth.

Answer:

(b) A copper rod.

2. When a glass rod is rubbed with a piece of silk cloth the rod

(a) and the cloth both acquire positive charge.

(b) becomes positively charged while the cloth has a negative charge.

(c) and the cloth both acquire negative charge.

(d) becomes negatively charged while the cloth has a positive charge.

Answer:

(b) becomes positively charged while the cloth has a negative charge.

3. Write T against true and F against false in the following statements:

(a) Like charges attract each other (T/F)

(b) A charged glass rod attract a charged plastic straw (T/F)

(c) Lightning conductor cannot protect a building from lightning (T/F)

(d) Earthquakes can be predicted in advance (T/F)

Answer:

(a)-f (b)-t (c)-f (d)-f

4. Sometime, a crackling sound is heard while taking off sweater during winters. Explain.

Answer:

A crackling sound is heard because when the sweater is rubbed while taking it, off, it acuquires a small charge.

5. Explain why a charged body loses its charge if we touch it with our hand.

Answer:

Our body is a conductor of electricity. When we touch a charged body loses charge to the earth through our body.

6. Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?

Answer:

The destructive energy of an earthquakq is measured on a scale called Richter scale. 

An earthquake that meausure 3 on the Richter scale will be recorded by seismograph However, it is not likely to cause much damage.

7. Suggest three measures to protect ourselves from lightning.

Answer:

(i) We should rush to a safer place like house or building.

(ii) 

8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

Answer:

A charged ballon is replled by another ballon beecause both have the same charge. And we know similar charges repel each oother.

Butt a charged ballon attracts an uncharged ballon and lose itts own charge too the other ballon. 

9. Describe with the help of a diagram an instrument which can be used to detect a charged body.

10. List three states in India where earthquakes are more likely to strike.

Answer:

The states that fall in seismic zones are more earthquake-prone. Jammu and Kashmir, Himachal Pradesh, and Gujrat are a few such states.

 

Additional Questions With Solutions:

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Ques: How does lightning produce?

Ans: Lightning is caused by the accumulation of charges in the clouds.

Ques: What is lightning?

Ans: Lightning is a natural phenomenon which occurs in the sky h clouds sparkwit.

Ques: Define charged object?

Ans: When a plastic comb is rubbed with dry hair, it acquires a small charge. These objects are called charged objects.

Ques: Write the type of charge?

Ans: (i) Positive charge         (ii)   Negative charge

Ques: Name the charge acquired by a glass rod when it is rubbed with silk.

(i) Charge on glass rod.

(ii) Charge on silk.

Ans:

(i) Charge on glass rod – Negative

(ii) Charge on silk – Positive

Ques: What is electroscope?

Ans: This is a device by which it is identified of charge on an object is carrying or not. This device is known as electroscope.

Ques: what is earthing?

Ans: The process of transferring of charge from a charged object to the earth is called earthing.