15. Some Natural Phenomena Science class 8 exercise Additional Questions With Solutions
15. Some Natural Phenomena Science class 8 exercise Additional Questions With Solutions ncert book solution in english-medium
NCERT Books Subjects for class 8th Hindi Medium
Chapter Review
Chapter Review:
- 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.
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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.
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The outermost layer of the earth is not in one piece. It is fragmented. Each fragment is called a plate.
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The plates are the weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones.
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The power of an earthquake is expressed in terms of a magnitude on a scale called Richter scale.
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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.
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Earthquake is caused by a disturbance deep inside the earth’s crust.
Text Book Exercise
Exercise
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.
Text Book Exercise
Exercise
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
Additional Questions With Solutions:
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.
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Science Chapter List
1. Crop Production And Management
2. Microorganisms : Friend And Foe
3. Synthetic Fibres And Plastics
4. Materials : Metals And Non-Metals
5. Coal And Petroleum
6. Combustion And Flame
7. Conservation of Plants And Animals
8. Cell - Structure and functions
9. Reproduction in animals
10. Reaching the age of adolescence
11. Force And Pressure
12. Friction
13. Sound
14. Chemical Effects of Electric Current
15. Some Natural Phenomena
16. Light
17. Stars And The Solar System
18. Pollution of Air and Water
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