A `120 V` house circuit has the following light bulbs switched on : `40 W, 60 W` and `75 W`. Find the equivalent resistance of these bulbs.

Answer

A, B

Explanation

`P=V^2/R`
`:. R=V^2/P`
`R_1=((120)^2)/40=360Omega`
`R_2=((120)^2)/60=240Omega`
`R_3=((120)^2)/75=192Omega`
Now, all these resistors are in parallel.