Q12 of 27 Page 1

Two lamps, one rated 100 W at 220 V and the other 200 W at 220V are connected (i) in series and (ii) in parallel to main electric supply of 220V. Find the current drawn in each case.

Given:

Voltage Rating of both lamps, V = 220 V


The power rating of first Lamp, P1 = 100 W


Power Rating of the second lamp, P2 = 200 W


To find: Current drawn in each case


Solution:





= 484 ohms





= 242 ohms


For series resistance, we know that equivalent resistance is given by,


Req = R1 + R2


= 242 + 484


= 726 ohms


So by Ohm’s Law we know that,


V = I× Req


I = V / Req



I = 0.3 A


For parallel connection, the equivalent resistance (Req) is given by,






Req = 161.33 ohms


So by Ohm’s Law we know that,


V = IReq


I = V / Req


I = 220 / 161.33


I = 1.36 A


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