Question

Assertion : The sensitivity of a moving coil galvanometer is increased by placing a suitable magnetic material as a core inside the coil.
Reason : Soft iron has high magnetic permeability and cannot be easily magnetized or demagnetized.

• A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
• B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
• C. If Assertion is correct but Reason is incorrect
• D. If both the Assertion and Reason are incorrect

Answer 1

Answer: (C)

Sensitivity of galvanometer,
$s = \frac{\theta}{i} \simeq \frac{\tan \theta}{i} = \frac{\mu_0 N}{2 R B_H}$
If a magnetic material is placed inside coil of galvanometer, then
$s' = \frac{\mu_r \mu_0 N}{2RB_H}$