A galvanometer has a coil of resistance 100 ohm and gives

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A galvanometer has a coil of resistance 100 ohm and gives a full-scale deflection for 30 mA current. It is to work as a voltmeter of 30 volt range, the resistance required to be added will be

1. 900Ω
2. 1800Ω
3. 500Ω
4. 1000Ω

Correct Option: A

Let the resistance to be added be R, then 30 = I_g (r + R)

∴ R =	30	- r =	30	- 100
	I_g		30 × 10³

= 1000 – 100 = 900 Ω