Question

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

Answer 1

FOR LAMP 1:  I₁ = \(\frac{P_1}{V}\) = \(\frac{100}{220}\) = \(\frac{5}{11}\) A 

FOR LAMP 2:  I₂ = \(\frac{P_2}{V}\) = \(\frac{60}{220}\) = \(\frac{3}{11}\) A 

∴ Net current = I₁+ I₂ 

= \(\frac{3}{11}\) + \(\frac{5}{11}\) 

=  \(\frac{8} {11} \)

= 0.73 A 

∴ Net current through the circuit is 0.73 A.