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

A 100 W, 200 V bulb is connected to a 160 volt supply.

The actual power consumption would be 64 W.

64 W

Given,

Resistance of the bulb R= $PV^{2}$  

where P=100W and V=200 V.

Therefore,

R= $\frac{(200^{2} )}{100}$= 400Ω

Actual power consumption P'= $\frac{V_{1} ^{2} }{R}$

where $V_{1}$ = 160V

∴ P = $\frac{(160^{2}) }{400\\}$ = 64 W

Therefore, the actual power consumption would be 64 W.