Friday 17 May 2013

Two lamps, one rated 100 W at 220 V and the other 60 W at 220 V



Question 15:
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Solution:
Both the bulbs are connected in parallel. Therefore, potential difference across each of them will be same that is 220 V, Current drawn by the bulb of rating 100 W is given by
I=P/V
 =100/220=0.4545...A
Similarly, current drawn by the bulb of rating 60 W is given by
I=P/V
 =60/220=0.2727...A
the total current drawn from the line =0.4545+0.2727=0.727A

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