Question

Scale of galvanometer divided into 100 equal divisions has a current sensitivity 10 div/mA and voltage sensitivity 4 div/mV. The resistance of the galvanometer is

• A. 5 \( \Omega \)
• B. 2.5 \( \Omega \)
• C. 10 \( \Omega \)
• D. 7.5 \( \Omega \)

Hint:

To determine the resistance of a galvanometer from its sensitivity, use the relationship between current sensitivity, voltage sensitivity, and the full-scale voltage and current.

Answer 1

The Correct Option is B

Step 1: Understanding the given values.
Current sensitivity \( S_I = 10 \) div/mA and voltage sensitivity \( S_V = 4 \) div/mV. The resistance of the galvanometer can be determined from the voltage sensitivity. The voltage sensitivity \( S_V \) is given by: \[ S_V = \frac{V_{\text{full scale}}}{I_{\text{full scale}}} = \frac{S_I}{S_V} \] Substituting the values: \[ S_V = \frac{10}{4} = 2.5 \, \Omega \] Step 2: Conclusion.
Thus, the resistance of the galvanometer is 2.5 \( \Omega \), which is option (B).