JEE Main 12 Jan 2019 Evening Question 25
Question: A galvanometer, whose resistance is 50 ohm, has 25 divisions in it. When a current of $ 4\times {10^{-4}} $ A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should be connected to a resistance of
[JEE Main Online Paper Held On 12-Jan-2019 Evening]
Options:
A) 200 ohm
B) 6250 ohm
C) 6200 ohm
D) 250 ohm
Show Answer
Answer:
Correct Answer: A
Solution:
- The full scale deflection current $ I _{g}=25\times 4\times {10^{-4}}A $
Let R be the resistance connected $ I _{g}=\frac{V}{R+R _{g}}\Rightarrow 25\times 4\times {10^{-4}}=\frac{2.5}{R+50} $
$ \Rightarrow $ $ R=200\Omega $
