Electricity — Question 15

As the two lamps are connected in parallel, the voltage across each of them will be the same.

Let I₁ be the current drawn by 100 W bulb:

I₁ = $\dfrac{\text{P}}{\text{V}} = \dfrac{100}{220} = \dfrac{5}{11} \text{ A}$

Let I₂ be the current drawn by 60 W bulb:

I₂ = $\dfrac{\text{P}}{\text{V}} = \dfrac{60}{220} = \dfrac{3}{11} \text{ A}$

∴ Current drawn from line = I₁ + I₂

$= \dfrac{5}{11} + \dfrac{3}{11} \\[1em] = \dfrac{5 + 3}{11} \\[1em] = \dfrac{8}{11} \text{ A} \\[1em] = 0.727272 \text{ A} \approx 0.73 \text{ A}$

Hence, 0.73 A current flows through the line.