If voltage across a bulb rated 220 Volt-100 Watt drops by

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If voltage across a bulb rated 220 Volt-100 Watt drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is :

1. 20%
2. 2.5%
3. 5%
4. 10%

Correct Option: C

Resistance of bulb is constant

P =	V²	⇒	ΔP	=	2ΔV	=	+	ΔR
	R		P		V			R

	ΔP	= 2 x 2.5 + 0 = 5%
	P