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

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?

 

Answer:-

Resistance R1 of the bulb is given by the expression,
Supply voltage, V = 220 V
Maximum allowable current, I = 5 A
Rating of an electric bulb P=10watts
Because R=V2/P
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According to Ohm’s law,
= I R
Let R is the total resistance of the circuit for x number of electric bulbs
R=V/I
   =220/5=44 Ω
Resistance of each electric bulb, R1=4840Ω
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∴ Number of electric bulbs connected in parallel are 110.