Question

A PMMC voltmeter has an available maximum voltage deflection (full scale deflection) current of 50 μA. If the meter has a range of 50 V and the coil resistance is 100 Ω, what will be the sensitivity of the voltmeter?
1. 20 kΩ/V
2. 10 kΩ/V
3. 40 kΩ/V
4. 100 kΩ/V

Answer 1

Correct Answer - Option 1 : 20 kΩ/V

Concept:

Sensitivity of voltmeter is given by,

\(s = \frac{1}{{{I_{FSD}}}}\)

Where I_FSD is full-scale deflection.

Calculation:

Given:

Full-scale deflection current, \({I_{FSD}} = \frac{1}{s} \)

Where, (s) is sensitivity.

\(s = \frac{1}{{{I_{FSD}}}}\)

\(s = \frac{1}{{50 \times {{10}^{ - 6}}}} = 20k{\rm{\Omega }}/V\)