Seismograph is used for :

Question

Accepted Answer

A seismograph is an instrument specifically designed to detect and record the vibrations and movements of the Earth's surface, which are typically caused by seismic waves generated during an earthquake. This makes Option 2, "To measure earthquake," the correct answer. Here's a detailed explanation:

1. **Why Option 2 is Correct:**
   - A seismograph works by having a mass suspended on a spring or pendulum. When the ground shakes due to seismic activity, the base of the seismograph moves, but the mass tends to remain stationary due to inertia. This relative motion between the mass and the base is recorded, providing data on the intensity, duration, and frequency of the earthquake.
   - Seismographs are crucial for monitoring and studying earthquakes, helping scientists understand the Earth's internal processes and assess potential risks in earthquake-prone areas.

2. **Why the Other Options are Incorrect:**
   - **Option 1: To measure speed of cyclone**
     - Cyclones are atmospheric phenomena, and their speed is typically measured using meteorological tools like anemometers, satellites, and Doppler radar, not seismographs. Seismographs are not designed to detect or measure atmospheric conditions.
   
   - **Option 3: To measure rainfall**
     - Rainfall is measured using instruments such as rain gauges, which collect and quantify precipitation over a set period. Seismographs do not have the capability to measure or record rainfall as they are not designed to interact with or measure liquid precipitation.
   
   - **Option 4: To measure charge on any metal rod**
     - The measurement of electrical charge on a metal rod is typically done using devices like electrometers or voltmeters. Seismographs are not equipped to measure electrical properties or charges, as their primary function is to detect ground motion.

In summary, a seismograph's primary and specialized function is to measure and record the seismic waves generated by earthquakes, making Option 2 the correct and only suitable choice.