Name: Protection Against Earthquakes
Uploaded: 2019-07-19
Duration: 2 min 28 s
Description: An earthquake is the shaking of the earth caused by the sudden movement of rock materials below the earth's surface. Let's see how we can protect ourselves during an earthquake.

Question

What is a seismograph? Explain its construction and working principle.

Accepted Answer

A seismograph or seismometer is an instrument used to detect and record earthquakes.

Working principle of the seismograph:

The disturbances or tremors energy originating from deep inside the Earth during an earthquake, shake the Earth’s surface. This shaking produces waves on the surface of Earth called seismic waves. The seismic waves can be detected on the ground with the help of a very sensitive instrument called a seismograph. They work on principle of pendulum and making use of inertia.

The labelled diagram of a seismograph is shown below:

As shown in the above figure, A seismograph consists of a pendulum with a metallic string hanging from a base attached to the Earth’s surface. While vibrating, the string of the pendulum moves within the poles of a horseshoe magnet. A pen is attached on the bottom side of the pendulum’s bob. A graph paper rolled on a rotating drum is kept below the pen. When an earthquake occurs, its shake cause the seismograph pendulum to oscillate and the sheet is fixed at to the ground. The relative change in the motion of the pendulum and the surroundings gives the magnitude of the earthquake.

What is a seismograph? Explain its construction and working principle.

Important Questions on Earthquakes

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