Magnetics Ques 134
- The resistance of a galvanometer is $50$ $ ohm$ and the maximum current which can be passed through it is $0.002$ $ A$. What resistance must be connected to it in order to convert it into an ammeter of range $0-0.5$ $ A$ ?
(a) $0.2 $ $ohm$
(b) $0.5 $ $ohm$
(c) $0.002 $ $ohm$
(d) $0.02 $ $ohm$
(2019 Main, 9 April II)
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Answer:
Correct Answer: 134.(a)
Solution:
Formula:
- Key Idea: An ammeter is a type of galvanometer with a shunt connected in parallel to the galvanometer.
Ammeter circuit is shown in the figure below,
So, $ \quad I _g G=\left(I-I _g\right) S $
Here,
$ \begin{aligned} I _g & =0.002 A \\ I & =0.5 A, \end{aligned} $
$ G=50 \Omega $
So, shunt resistance required is
$ S=\frac{I _g G}{I-I _g}=\frac{0.002 \times 50}{(0.5-0.002)} \approx 0.2 \Omega $
BETA
