### Chapter 3: Electricity

Q
##### Electricity

Question:

Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?

The lamps are connected in parallel, so the voltage across each lamp will be 220 V because the voltage is the same in a parallel circuit.

For 100 W lamp, the current drawn is given by,

$P = VI$

$I = \frac{P}{V}$

Given: $V = 220\ V, P = 100\ W$

$I_1 = \frac{100}{220}\ A$

Similarly, for 60 W lamp

$V = 220\ V, P = 60\ W$

$I_2 = \frac{60}{220}\ A$

Total current,$I = I_1 + I_2$

$I = \frac{100}{220} + \frac{60}{220}$

$I = \frac{160}{220}$

$I = \frac{8}{11}$

$I = 0.727\ A$

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