MCQ
Consider a moving coil galvanometer (MCG) :
A : The torsional constant in moving coil galvanometer has dimensions $\left[ ML ^2 T^{-2}\right]$
B : Increasing the current sensitivity may not necessarily increase the voltage sensitivity.
C : If we increase number of turns $( N )$ 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 :
  • A, B only
  • B
    A, D, only
  • C
    B, D, E only
  • D
    A, B, E only

Answer

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

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