# Electromagnetism

## An instrument which can measure potential without drawing any current is

A.voltmeter B.galvanometer C.cathode ray oscilloscope (CRO) D.ammeter

## Galvanometer is a very sensitive device with

A.very low damping B.very high damping C.no damping at all D.radial field disintegration

## The deflection for 50 division of galvanometer is decreased to 25 divisions by shunt resistance of 12?. Galvanometer resistance is

A.18? B.30? C.24? D.12?

## Which one of the following methods would be able to increase the sensitivity of a moving coil galvanometer ?

A.connect a shunt across the coil B.use a coil of smaller cross sectional area C.use a coil having less number of turns D.use spiral springs whose force constant is small

## When the coil of the galvanometer is in equilibrium then the deflecting couple is

A.zero B.equal to the restoring couple C.greater than the restoring couple D.smaller than the restoring couple

## Heating a magnet will

A.weaken it B.strengthen it C.reverse its polarity D.demagnetize it completely

## The sensitivity of a galvanometer is given by

A.C/BAN B.CAN/B C.BAN/C D.ABC/N

## If a current carrying solenoid is suspended freely it will

A.be rotating B.come to rest in N-S direction C.vibrating like galvanometer needle D.comes to rest after rotation

## Which one of the following is not an electromechanical instrument?

A.galvanometer B.voltmeter C.ammeter D.AC transformer and DC generator

## Minimum current required to produce a deflection of 1 mm on a scale at a distance of 1 meter is

A.0.1 A B.1:00 AM C.current sensitivity D.1 m A