Question

An ammeter requires a change of 3 A in its coil to produce a change in deflection of the pointer by 12 mm. Its sensitivity is
1. 15 mm/A
2. 9 mm/A
3. 4 mm/A
4. 36 mm/A

Answer 1

Correct Answer - Option 3 : 4 mm/A

Concept

The sensitivity of ammeter is defined as the current required for full-scale deflection of the ammeter scale.

\(Sensitivity = \frac{{Changeindeflectionofpointer}}{{Changeofcurrent}}\)

Calculation

Given

Change of current = 3 A

Change in deflection of pointer = 12 mm

\(Sensitivity = \frac{{Changeindeflectionofpointer}}{{Changeofcurrent}}\)

\(\frac{{12}}{3} = 4mm/A\)