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Q.12.    Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220 V line if the maximum allowable current is 5 A?


Answers (1)


Given: V=220V and P=10W


Let x be the number of bulbs.

I = 5A              and      V=220V


For x bulbs of resistance 4680 Ohm, are connected in parallel to obtain 44 Ohm equivalent resistance.


         \frac{1}{R}=\frac{1}{4840}+\frac{1}{4840}\, \, x\, \, times

\Rightarrow \frac{1}{44}=\frac{x}{4840}

\Rightarrow x=\frac{4840}{44}=110

Hence, 110 bulbs  of 4840 Ohm are connected in parallel to obtain 44 Ohm

Posted by

seema garhwal

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