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 the 220 V line if the maximum allowable current is 5 A?

Asked by Vishal kumar | 2 years ago |  212

1 Answer

Solution :-

The resistance of the bulb can be calculated using the expression

P1 = V2 /R1

R1 = V2 /P1

Substituting the values, we get

\( R= \frac{(220)^2}{10}=4840\,\Omega\)

The resistance of x number of electric bulbs is calculated as follows:

\( R = \frac{V}{I}= \frac{220}{5}=44\,\Omega\)

\( The\, resistance \,of \,each\, electric\, bulb \,is \,4840\,\Omega\)

The equivalent resistance of x bulbs is given by

\(\frac{1}{R}= \frac{1}{R_1}+\frac{1}{R_1} +\frac{1}{R_1}\pm ....upto\,x\,times\)

\( \frac{1}{R}= \frac{1}{R_1}\times x\)

\( x= \frac{R_1}{R}= \frac{4840}{44}=110\)

Hence, 110 lamps can be connected in parallel.

Answered by Shivani Kumari | 2 years ago

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