Question

The coil of a galvanometer consists of 100 turns and effective area of 1 square cm. The restoring couple is 10^{– 8} N-m rad. The magnetic field between the pole pieces is 5 T. The current sensitivity of this galvanometer will be

• A. 5 × 10⁴ rad/μ amp
• B. 5 × 10^{– 6} per amp
• C. 2 × 10^{– 7} per amp
• D. 5 rad./μ amp

Answer 1

Answer: (D)

5 rad./μ amp

Answer 2

Current sensitivity (S_i) = $\frac { \theta } { i } = \frac { N B A } { C }$

⇒ $\frac { \theta } { i } = \frac { 100 \times 5 \times 10 ^ { - 4 } } { 10 ^ { - 8 } } = 5 \mathrm { rad } / \mu \mathrm { amp }$.