Question

write the principle and working of an ideal voltmeter. Name it. How can the sensitivity of this instrument be increased?

Answer 1

Dear Student,

Voltmeter works as an instrument which is used to measure potential difference. Voltmeter is basically a galvanometer with a high value of resistance. When a suitable high resistance is connected in series with Galvanometer, very negligible current flows through it. By selecting a proper series resistance, we can increase the range of potential to be measured by galvanometer.

Working: When the current flows through the voltmeter(galvanometer). The current is passed through a coil in a magnetic field, the coil experiences a torque proportional to the current. If the coil's movement is opposed by a coil spring, then the amount of deflection of a needle attached to the coil may be proportional to the current passing through the coil.

The sensitivity can be increased by
1) Increasing number of turns
2) Reducing the torsional constant of spring used.
3) Increasing area of coil
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Regards,