Consider a moving coil galvanomenter (MCG): A. The torsional constant in moving coil galvanometer has…

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

Solution

(A) $\tau=\mathrm{C} \theta \Rightarrow\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right]=[\mathrm{C}][1]$
(B) $\mathrm{C}. \mathrm{S}=\frac{\theta}{\mathrm{I}}=\frac{\mathrm{BNA}}{\mathrm{C}}$;
V.S. $=\frac{\mathrm{BNA}}{\mathrm{RC}}[\mathrm{R}$ also depends on ' N ']
(C) V.S. $\propto \frac{\mathrm{NAB}}{\mathrm{CR}} \quad \mathrm{R} \rightarrow \mathrm{NR}$
(D) False [Theory]
(E) E [False]
$\mathrm{C}. \mathrm{S} \propto \mathrm{~N}$
$\Rightarrow \because \mathrm{C}. \mathrm{S}.=\frac{\mathrm{NAB}}{\mathrm{C}}$

Asked in: JEE Main 2025 (23 Jan Shift 1)

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