Question

Consider a moving coil galvanometer (MCG):
A : The torsional constant in moving coil galvanometer has dimensions \( [ML^2 T^{-2}] \)
B : Increasing the current sensitivity may not necessarily increase the voltage sensitivity.
C : If we increase the number of turns (N) to its double (2N), then the voltage sensitivity doubles.
D : MCG can be converted into an ammeter by introducing a shunt resistance of large value in parallel with the galvanometer.
E : Current sensitivity of MCG depends inversely on the number of turns of the coil.
Choose the correct answer from the options given below:

• A. A, B only
• B. A, D, only
• C. B, D, E only
• D. A, B, E only

Hint:

To determine the behavior of an MCG, remember that voltage sensitivity and current sensitivity depend on factors like the number of turns, torsional constant, and the shunt resistance, which can modify its properties.

Answer 1

The Correct Option is A

Explanation:

In the given question, we have to evaluate the statements related to the properties and functioning of a moving coil galvanometer (MCG):

• Statement A: The torsional constant in moving coil galvanometer has dimensions \([ML^2 T^{-2}]\). This is correct. The torsional constant is a measure of the coil's resistance to twisting, and the dimensions match those of energy per radian.
• Statement B: Increasing the current sensitivity may not necessarily increase the voltage sensitivity. This is true because current sensitivity depends on the number of turns and the magnetic field, whereas voltage sensitivity also depends on the coil resistance.
• Statement C: If we increase the number of turns (N) to its double (2N), then the voltage sensitivity doubles. This is not necessarily correct, as it assumes constant resistance, which might not hold if the number of turns increases.
• Statement D: MCG can be converted into an ammeter by introducing a shunt resistance of large value in parallel with the galvanometer. This is incorrect; a small value shunt resistance is used to allow most of the current to bypass the galvanometer.
• Statement E: Current sensitivity of MCG depends inversely on the number of turns of the coil. This is incorrect; current sensitivity actually depends directly on the number of turns.

Conclusion: Based on the analysis, only statements A and B are correct.

Correct Answer: A, B only