Class 8 Science Lesson 15 Inside Question and Answer NCERT & CBSE Board Here in this post. NCERT Class 8 Science Textbook Lesson 15 Inside Questions.
- Grade: VIII
- Lesson 15 Some Natural Phenomena
Que. 1) Fill in the blanks.
(1) The power of an earthquake is expressed in terms of a magnitude on a scale called——-
Ans- Ritcher scale.
(2) There are two kinds of charges —- and —–
Ans –positive and negative .
(3) The electrical charges produces by rubbing are called——-
Ans- static charges.
(4) Earthquake caused by a disturbance deep inside the ——-
Ans- earth crust
Que. 2) answer the following question.
(1) Define the following
- Electroscope – A device can be used to test whether an object is carrying charge or not, this device is known as Electroscope.
- Earthing- The process of transferring of charge from a charged object to the earth is called Earthing.
- Seismic waves-The termors produce waves on the surface of the earth these are called seismic waves.
- Ritcher scale- The power if an earthquake is expressed in terms of a magnitude on a scale called the Ritcher scale.
(2) What is an earthquake?
Ans-An earthquake is a natural phenomenon in which sudden shaking or disturbing of the earth surface and which lasts for a very short time known as an Earthquake. It is caused by a disturbance deep inside the earth’s crust. Earthquake occur all the time ,all over the earth. They are not even noticed. Major earthquake are much less frequent. Earthquake can causes immense damage to buildings, bridges, dams and people. Because of it shows great loss to life and property. Earthquake can cause floods, landslides and tsunamis.
(3) Write short note on seismic waves and seism graph.
Ans- The tremors produce waves on the surface of the earth these are called seismic waves. The waves are recorded by an instruments called the seismograph.
Seismograph-It is an instruments which include simply a vibrating rod, or a pendulum, which starts vibrating when termors occur. A pen attached to the vibrating system. The pen records the seismic waves on a paper which moves under it. By studying these waves, scientist can construct a complete map of the earthquake. They can also estimate its power to cause destruction.
(4) What protection you take at the time of earthquake
If you are at home- at the time of earthquake if you are at home then 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-at the time of earthquake if you are at outdoors then 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 slowely to a clear spot. Do not come out till the tremors stop.
(5) Name the danger zone of an earthquake in India.
Ans-In India the areas most threatened are Kashmir, western and central Himalayas, the whole of north-east, ran of kutch, Rajasthan and Indo – Gangetic plane. Some areas of south India also fall in the danger zone. This are the some danger zones in India.