Question

(a) Define electric power. An electrical device of resistance R is connected across a source of voltage V and draws a current I. Derive an expression for power in terms of current and resistance.
(b) Two electric bulbs rated 100 W; 220 V and 60 W; 220 V are connected in parallel to electric mains of 220 V. Find the current drawn by the bulbs from the mains.

Answer 1

Hope this helps you. .

- Khushali.S.S. .

Answer 2

Explanation:

Solution :

(a) Electric Power . Electric Power is the rate at which work is done or enegy is transformed in an electric circuit. <br> We know that electric work done is , <br>

<br>

<br> As per Ohm's law , V= IR <br> Substituting (i) in the power formula . <br> We get . <br>

.... where [I is the current , R is the resistance. <br> (b) Resistance of

bulb. <br>

<br> Resistance of

bulb, <br>

<br> Total Resistance in parallel, <br>

<br>

. <br> current darwn by the bulbs from the main line . <br>