Question

several electric bulb designed to be used on 220 V electric supply rated at 10 W. how many lamps can be connected in parallel with each other across tow wires of 220 V line if maximum allowed current is 5A?

Answer 1

let let there be X bulbs

V=220v

I=5A

by using power formula P =VI

10x=220*5

x=22*5

no of bulbs are 110

Answer 2

Explanation:

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

According to Ohm’s law,

V = 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

∴ Number of electric bulbs connected in parallel are 110.