Question

) A 100 W, 200 V bulb is connected to a 160 volt supply. The actual power consumption would be *

64 W

125 W

100 W

80 W​

Answer 1

Resistance of bulb=$R=\frac{V²}{P}$

where $P=100\:W$ and $V=200\: V.$

$\therefore\:R=\frac{(200)²}{100}=400\:Ω$

Actual power consumption =$P'=\frac{{V_1}^{2}}{R}$

where,

$R = 400\:Ω$

$V_1 = 160\:V$

$\therefore P'=\frac{(160)²}{400}= 64\:W$

$\underline{\boxed{\sf{actual \: power \: consumption \: = \: 64 \: W }}}$