A light bulb is rated 100W for 220 V AC supply of 50 Hz. Calculate (a) resistance of the bulb. (b) the rms current through the bulb.

the given can be listed as

Power P = 100W

$V_{rms}=220 V$

To Find , Resistance R = ?

$I_{rms}=?$

Solution -

$R=\frac{V_{rms}^{2}}{P}=\frac{220\mathrm{x}220}{100}=484\Omega$

$I_{rms}=\frac{P}{V_{rms}}=\frac{100}{220}=\frac{1}{2.2}=0.45A$

Two trains, one travelling at 15 m/s and the other at 20m/s are headed towards each other on a level track. When they are 2km apart, both drivers apply brakes. If their brakes produce retardation of0.20m/s² what is the final separation?