Moving Charges and Magnetism - Result Question 83

85. A galvanometer of 50ohm resistance has 25 divisions. A current of 4×104 ampere gives a deflection of one per division. To convert this galvanometer into a voltmeter having a range of 25 volts, it should be connected with a resistance of

[2004, 2002]

(a) 2450Ω in series

(b) 2500Ω in series.

(c) 245Ω in series.

(d) 2550Ω in series.

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Answer:

Correct Answer: 85. (a)

Solution:

  1. (a) Rg=50Ω,Ig=25×4×10AΩ=102A Range of V=25 volts

V=Ig(Re+Rg)Re=VIgRg=2450Ω

In order to increase the range of voltmeter n times the value of resistance to be connected in series with galvanometer is

R=(n1)G

Here, G= resistance of galvanometer



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