Question

Two lamp tayes 100w at 220v are connected parallel to 220v main supply.calculate the current drawn from the supply line?

Answer 1

p=100
v=220

p=vi
i=p/v
100/220
=5/11
0.45

Answer 2

$power \: of \: lamp = 100w \\ voltage \: across \: each \: lamp = 220v \\ current \: drawn \: by \: single \: lamp = \frac{p}{v} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{100}{220} = \frac{5}{11} \\ in \: parallel \: connection \: current \: is \: divided \\ \: among \: two \: lamps. \\ so \: total \: current \: \: = 2i = 2 \times \frac{5}{11 } \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{10}{11} = 0.909$