JEE Mains · Physics · STD 12 - Moving charges and magnetism
- JEE Mains 2025
- Medium
- MCQ
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:
Pick an option to check your answer.
Answer & Solution
Correct Answer
(D) A, B Only
Step-by-step Solution
Detailed explanation
(A) \(\tau=\mathrm{C} \theta \Rightarrow\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right]=[\mathrm{C}][1]\)
(B) \(\mathbf{C} . \mathrm{S}=\frac{\theta}{\mathrm{I}}=\frac{\mathrm{BNA}}{\mathrm{C}}\);
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]
\(\mathrm{C} . \mathrm{S} \propto \mathrm{~N}\)
\(\Rightarrow \because \mathrm{C} . \mathrm{S} .=\frac{\mathrm{NAB}}{\mathrm{C}}\)
(B) \(\mathbf{C} . \mathrm{S}=\frac{\theta}{\mathrm{I}}=\frac{\mathrm{BNA}}{\mathrm{C}}\);
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]
\(\mathrm{C} . \mathrm{S} \propto \mathrm{~N}\)
\(\Rightarrow \because \mathrm{C} . \mathrm{S} .=\frac{\mathrm{NAB}}{\mathrm{C}}\)
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