Question

A galvanometer of resistance ‘G’ can be converted into a voltmeter of range (0 − V) volt by connecting a resistance ‘R’ in series with it. The resistance ‘R’ required to change its range from `(0 - V/4)` volt will be ______.

विकल्प

• `(R - G)/2`

• `(R - 2G)/3`

• `(R - 3G)/4`

• `(4R - 3G)/5`

Answer 1

A galvanometer of resistance ‘G’ can be converted into a voltmeter of range (0 − V) volt by connecting a resistance ‘R’ in series with it. The resistance ‘R’ required to change its range from `(0 - V/4)` volt will be `bbunderline((R - 3G)/4)`.

Explanation:

For a voltmeter,

R + G = `V/I_s`

R' + G = `V/(4 I_s)    ...(because v = v/4)`

∴ `R' + G = (R + G)/4`

∴ R' = `(R - 3G)/4`