Question

The scale of a dynamometer type instrument marked in terms of RMS value would be__________

(a) Uniform throughout

(b) Non-uniform and crowded near the full scale

(c) Non-uniform and crowded at the beginning

(d) Non-uniform and crowded around mid-scale

This question was posed to me during an online interview.

The query is from Advanced Problems on Indicating Instruments topic in chapter Extension of Instrument Ranges of Electrical Measurements

Answer 1

Correct choice is (c) Non-uniform and crowded at the beginning

Explanation: We have deflection θ ∝ I^2 for an ammeter and θ ∝ V^2 for a voltmeter. We have assumed the value for the voltmeter to be constant but it is not true. The value is constant for a radical field but not for a voltmeter.