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` ?

Explanation

For one bulb : Power P = 10 W and Potential difference V = 220 V Using the relation for R, we have `R=(v)/(p)= (220)^(2)/(10) 4840 omega`
Let the total number of bulbs be x. Given that: Current I = 5 A and Potential Difference V = 220 V According to Ohm.s Law V = IR Now, for x number of bulbs of resistances 4840 `omega` the equivalent resistance of the resistors connected in parallel is 44 `omega`
`1/44=1/4840+1/4840+1/4840+`...to x times
`x=4840/44=110`
Therefore, 110 bulbs of 4840 `omega` are required to draw the given amount of current.