Question

If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is ______.

Options

• 68.4 W

• 45.8 W

• 10.6 W

• 29.5 W

Answer 1

If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is 68.4 W.

Explanation:

P = `"v"^2/"R" => "R" = "v"^2/"P"`

`"R"_1 = 220^2/1000, "R"^2 = 220^2/100`

`"R"_"series" = "R"_1 + "R"_2 = (220^2 xx 11)/1000`

Current (i) = `"v"/"R"_"series" = (200 xx 1000)/(220^2 xx 11)`

Power consumed by bulb = i²R₂ = 68.4 W