Some Natural Phenomena Class 8 Extra Questions and Answers

These AP 8th Class Physics Important Questions and 9th Lesson Some Natural Phenomena Class 8 Extra Questions will help students prepare well for the exams.

Class 8 Science Some Natural Phenomena Extra Questions

Some Natural Phenomena Class 8 Important Questions

Question 1.
Write any two destructive natural phenomena.
Answer:
Lightning and earthquakes are two destructive natural phenomena.

Question 2.
What is lightning caused by ?
Answer:
Lightning is caused by the accumulation of charges in the clouds.

Question 3.
What is shown by Benjamin Franklin regarding lightning ?
Answer:
Benjamin Franklin, an American scientist, showed that lightning and the spark from your clothes ard essentially the same phenomena.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 4.
What is an electroscope ?
Answer:
An electroscope is a device that can be used to test whether an object is carrying a charge or not.

Question 5.
What is the working principle of an electroscope ?
Answer:
Electrical charge can be transferred from a charged object to another through a metal conductor.

Question 6.
What is earthing ?
Answer:
The process of transferring charge from a charged object to the earth is called earthing.

Question 7.
What is the use of earthing in our daily life ?
Answer:
Earthing is provided in buildings to protect us from electrical shocks due to any leakage of electrical current.

Question 8.
Why do we take measures while lightning ?
Answer:
A lightning strike could destroy life and property. It is, therefore, necessary to take measures to protect ourselves.

Question 9.
What do you do when you are travelling by a vehicle while lightning ?
Answer:
If you are travelling by car or by bus, you are safe inside with the windows and doors of the vehicle shut.

Question 10.
What is an Earthquake ?
Answer:
An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time caused by a disturbance deep inside the earth’s crust.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 11.
How do tremors occur ?
Answer:
The tremors are caused by the disturbance deep down inside the uppermost layer of the earth called the crust.

Question 12.
What are the parts of the inner earth ?
Answer:
Crust, mantle, outer core and inner core are the layers of the earth.

Question 13.
What are seismic or fault zones ?
Answer:
Since earthquakes are caused by the movement of plates, the boundaries of the plates are the weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones.

Question 14.
What is a Richter scale ?
(OR)
How does the power of an earthquake measure ?
Answer:
The power of an earthquake is expressed in terms of a magnitude on a scale called the Richter scale.

Question 15.
What type of material should be used to construct a house in a seismic zone ?
Answer:
In highly seismic areas, the use of mud or timber is better than using heavy construction material.

Question 16.
When does static become electric current ?
Answer:
When charges move, they constitute an electric current.

Some Natural Phenomena Class 8 Extra Questions and Answers

Some Natural Phenomena Extra Questions

Question 1.
How many types of electric charges are there ?
Answer:
There are two types of electric charges.
They are

  1. positive charge
  2. negative charge.

Question 2.
What do you observe when a charged glass rod is brought near a charged plastic straw rubbed with polythene ?
Answer:
It is observed that when a charged glass rod is brought near a charged plastic straw rubbed with polythene there is an attraction between the two.

Question 3.
What is a static electric charge ? What is its property ?
Answer:
The electrical charges generated by rubbing are static. They do not move by themselves.

Question 4.
Why do the aluminium strips repel in the electroscope, when it is touched by a charged object ?
(OR)
How does an electroscope work ?
Answer:

  1. The aluminium foil strips receive the same charge from the charged refill through the paper clip.
  2. The strips carrying similar charges repel each other and they become wide open.

Question 5.
What will happen if we touch the metal rod of the electroscope after the silver foils are charged ? Why ?
Answer:
The foil strips come together as soon as we touch the metal rod with our hands. The reason is that the foil strips lose charge to the earth through our bodies. We say that the foil strips are discharged.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 6.
What precautions do you take while lightning ?
Answer:

  1. During lightning and thunderstorm no open place is safe.
  2. Hearing thunder is an alert to rush to a safer place.
  3. After hearing the last thunder, wait for some time before coming out of the safe place.

Question 7.
What are Lightning Conductors? How do they work ?
(OR)
How do Lightning Conductors protect us from lightning streaks ?
Answer:

  1. Lightning Conductor is a device used to protect buildings from the effect of lightning.
  2. A metallic rod, taller than the building, is installed in the walls of the building during its construction.
  3. One end of the rod is kept out in the air and the other is buried deep in the ground.
  4. The rod provides an easy route for the transfer of electric charge to the ground.

Question 8.
Why do we not touch the metal objects used during construction while lightning ?
Answer:
The charge can transfer through the metal rods, pipes, etc., to the earth while lightning.
We may get an electric shock if we touch them. So, we do not touch the metal objects used during construction while lightning.

Question 9.
How do you appreciate the role of the weather department in protecting from thunderstorms ?
Answer:
The weather department can warn about a thunderstorm developing in some areas. If a thunderstorm occurs there is always a possibility of lightning and cyclones accompanying it. So, we get time to take measures to protect ourselves from the damage caused by these phenomena. So, I appreciate the weather department.

Question 10.
Why do earthquakes can cause damage to human life and property on a huge scale?
Answer:
Earthquakes are not yet able to predict accurately by the weather department. So, we cannot estimate the time and place where it would occur. So, it can cause damage to human life and property on a huge scale.

Question 11.
Write two major earthquakes that occurred in India.
Answer:
Major earthquakes that occurred in India are

  1. on 26 January 2001 in the Bhuj district of Gujarat.
  2. on 8 October 2005 in Uri and Tangdhar towns of North Kashmir.

Question 12.
What are the effects of the major earthquakes ?
Answer:

  1. Major earthquakes are much less frequent.
  2. They can cause immense damage to buildings, bridges, dams and people.
  3. There can be a great loss of life and property.
  4. Earthquakes can cause floods, landslides and tsunamis.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 13.
What causes the occurrence of a tsunami ? When did a major tsunami occur in India? How was it affected ?
Answer:

  1. Tsunami occurs after a major earthquake hit an ocean.
  2. A major tsunami occurred in the Indian Ocean on 26 December 2004.
  3. All the coastal areas around the ocean suffered huge losses.

Question 14.
What are the identified seismic zones in India ?
Answer:
The identified seismic zones in India are Kashmir, Western and Central Himalayas, the whole of North-East, Rann of Kutch, Rajasthan and the Indo-Gangetic Plain. Some areas of South India also fall in the danger zone.

Question 15.
What are seismic waves? How do they record ?
Answer:

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

Extra Questions of Some Natural Phenomena Class 8

Question 1.
How does lightning occur ?
(OR)
How does a thunderstorm occur ?
Answer:
Some Natural Phenomena Class 8 Extra Questions and Answers 1

  1. When the clouds move in the air, due to drag the positive charges collect near the upper edges of the clouds and the negative charges accumulate near the lower edges.
  2. There Is an accumulation of positive charges near the ground also.
  3. When the magnitude of the accumulated charges becomes very large, the air which is normally a poor conductor of electricity, is no longer able to resist their flow.
  4. Negative and positive charges meet, producing streaks of bright light and sound.
  5. We see streaks as lightning. The process is called an electric discharge.
  6. The process of electric discharge can occur between two or more clouds or between clouds and the earth.

Question 2.
What do you do when you are walking on an open ground while lightning ?
(OR)
How do you protect yourself from lightning if no shelter is available and you are in an open field ?
Answer:

  1. If no shelter is available and you are in an open field, stay far away from tall trees.
  2. Stay away from poles or other metal objects.
  3. Do not lie on the ground. Instead, squat low on the ground.
  4. Place your hands on your knees with your head between the hands.
  5. This position will make you the smallest target to be struck.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 3.
What do you do when you are in the house while lightning ?
Answer:
Inside the house :

  1. Lightning can strike telephone cords, electrical wires and metal pipes.
  2. During a thunderstorm contact with these should be avoided.
  3. It is not wise tb call up a person who is receiving your phone through a wired phone.
  4. Bathing should be avoided during thunderstorms to avoid contact with running water.
  5. Electrical appliances like computers, TVs, etc., should be unplugged.

Question 4.
Draw the diagram of the structure of the earth.
Answer:
Some Natural Phenomena Class 8 Extra Questions and Answers 2

Question 5.
What is an earthquake? How does it occur? Explain.
Answer:

  1. An earthquake is a sudden shaking or trembling of the earth.
  2. Earthquake is caused by a disturbance deep inside the earth’s crust.
  3. The outermost layer of the earth is not in one piece. It is fragmented.
  4. Each fragment is called a plate.
  5. These plates are in continual motion.
  6. When they brush past one another, or a plate goes under another due to collision, they cause disturbance in the earth’s crust.
  7. It is this disturbance that shows up as an earthquake on the surface of the earth.

Question 6.
Explain the working process of a seismograph with a neat diagram.
Answer:
Some Natural Phenomena Class 8 Extra Questions and Answers 3

  1. The seismic waves are recorded by an instrument called the seismograph.
  2. The instrument is simply a vibrating rod, or a pendulum, which starts vibrating when tremors occur.
  3. A pen is attached to the vibrating system
  4. The pen records the seismic waves on a paper which moves under it.
  5. By studying these waves, scientists can construct a complete map of the earthquake.
  6. They can also estimate their power to cause destruction.

Question 7.
It Is advisable to make the structure simple so that it is ‘Quake Safe’. What Is the recommended advice?
(OR)
What are the steps to be taken while constructing a house to protect from the
earthquake in the seismic zones ?
Answer:

  1. Consult qualified architects and structural engineers.
  2. In highly seismic areas, the use of mud or timber is better than using heavy construction material. Keep roofs as light as possible. In case the structure falls, the damage will not be heavy.
  3. It is better if the cupboards and shelves are fixed to the walls, so that they do not fall easily.
  4. Be careful where you hang wall clocks, photo frames, water heaters etc., so that in the event of an earthquake, they do not fall on people.
  5. Since some buildings may catch fire due to an earthquake, it is necessary that all buildings, especially tall buildings, have fire-fighting equipment in working order.

Question 8.
Write the precautions to take to protect yourself from an earthquake.
(OR)
How do you protect yourself from an earthquake when you are at home or, outdoor?
Answer:
If you are at home :

  1. Take shelter under a table and stay there till the shaking stops.
  2. Stay away from tall and heavy objects that may fall on you.
  3. If you are in bed, do not get up. Protect your head with a pillow.

If you are outdoors :

  1. Find a clear spot, away from buildings, trees and overhead power lines. Drop to the ground.
  2. If you are in a car or a bus, do not come out. Ask the driver to drive slowly to a clear spot. Do not come out till the tremors stop.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 9.
Fill in the table

Rubbing materials Positive charge Negative charge
Glass rod, Silk
Straw, Polythene
Dry hair, Comb Dry hair
Glass rod, Polyester Polyester
Amber, Wool

Answer:

Rubbing materials Positive charge Negative charge
Glass rod, Silk Glass rod Silk
Straw, Polythene Polythene Straw
Dry hair, Comb Dry hair Comb
Glass rod, Polyester Glass rod Polyester
Amber, wool Wool Amber

Question 10.
Draw the diagram of an electroscope.
Answer:
Some Natural Phenomena Class 8 Extra Questions and Answers 4

Question 11.
Draw the diagram of a seismograph.
Answer:
Some Natural Phenomena Class 8 Extra Questions and Answers 5

Question 12.
Explain the given natural phenomena
a) Lightning,
b) Earthquake.
Answer:
a) Lightning:

  1. The streaks produced between clouds in the process of an electric discharge through the air are called lightning.
  2. Lightning strikes could destroy life and property.
  3. During lightning and thunderstorm no open place is safe.
  4. A lightning conductor is a device used to protect buildings from the effect of lightning.

b) Earthquake :

  1. An earthquake is a sudden shaking or trembling of the earth which lasts for a very short time. It is caused by a disturbance deep inside the earth’s crust.
  2. Earthquakes occur all the time, all over the earth.
  3. They can cause immense damage to buildings, bridges, dams and people.
  4. There can be a ‘great loss of life and property.
  5. Earthquakes can cause floods, landslides and tsunamis.
  6. The power of an earthquake is expressed in terms of a magnitude on a scale called the Richter scale.The seismic waves are recorded by an instrument called the seismograph.
  7. Protection against Earthquakes : The buildings in the seismic zones should be.so designed that they can with stand major tremors.

Some Natural Phenomena Class 8 Extra Questions and Answers

Question 13.
How is the power of an earthquake estimated ? At what strength it becomes destructive ?
Answer:

  1. The power of an earthquake is expressed in terms of its magnitudes on a scale called Richter scale.
  2. The destructive earthquakes have magnitudes higher than about 7 on the Richter Scale.
  3. Both Bhuj and Kashmir earthquakes had magnitudes greater than 7.5.
  4. Like many other scales in science, Richter scale is not linear.
  5. This means that an earthquake of magnitude 6 does not have twice the destructive energy of an earthquake of magnitude 3.
  6. In fact, an increase of 2 in magnitude means 1000 times more destructive energy.
  7. For example, an earthquake of magnitude 6 has thousand times more energy than an earthquake of magnitude 4.
  8. Tremors on the earth can also caused when a volcano erupts, or a meteor hits the
    earth, or an underground nuclear explosion is carried out.
  9. However, most earthquakes are caused by the movement of the earth’s plate.

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