Consider a moving coil galvanomenter (MCG): A. The torsional constant in moving coil galvanometer has dimentions \(\left…
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 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:
[JEE Main 2025, 23 Jan (Shift 1)]
A, B Only
From t = Cθ, the torsional constant has the dimensional formula:
[ \(M{L}^{2}{T}^{-2}\) ]
(B) Current Sensitivity (C.S)
\(C.S=\frac{\theta }{I}=\frac{BNA}{C}\)
Voltage Sensitivity:
\(V.S=\frac{BNA}{RC}\)
Since R depends on N , increasing current sensitivity does not always increase voltage sensitivity.
(C) Voltage Sensitivity (V.S) Dependency
\(V.S\propto \frac{NAB}{CR}\)
If R also increases with N , voltage sensitivity does not necessarily double.
(D) Incorrect Theory
MCG to ammeter conversion requires low shunt resistance, not large.
(E) Current Sensitivity Dependency
\(C.S\propto N\)
Since C.S is directly proportional to N , the statement claiming an inverse relation is incorrect.
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