Question:

The net resistance of an ammeter should be small to ensure that

Updated On: Jun 14, 2022
  • it does not get overheated
  • it does not draw excessive current
  • it can measure large currents
  • it does not appreciably change the current to be measured
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The Correct Option is D

Solution and Explanation

Ammeter are designed to have a small internal resistor in order to measure the current passing on its branch without actually using any of it. Usually, it has a negligible internal resistance and voltage drop which is ideal to use for measurement approximations.
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Concepts Used:

Electrical Instruments

There are various electrical instruments used to measure current, power, voltage, etc.  Some of them are briefly explained below:

Moving Coil Galvanometer

  • It is an electromagnetic device which measures small values of current.
  • Its working principle is that whenever a current loop is placed in a magnetic field, it experiences a certain torque. The value of that torque can be modified by modifying the current in the loop.
  • For a current carrying loop having N turns, and cross sectional area A, carrying current i, whenever it is placed in and along the direction of an external magnetic field B, it experiences a torque given by:

ԏ = NiAB

moving coil galvanometer