Question

Find the ration of resistance of two bulbs having ratings `220V-60W` and `110V-6W` ?

Find the ratio of resistance of two bulbs having ratings `220V-60W` and `110V-6W` .

Answer 1

The ratio is `=0.4`

Explanation:

From the equations

`U=RI` and `P=UI`

`R=U/I=U^2/P`

For the first light bulb

`R_1=220^2/60=806.7Omega`

For the second light bulb

`R_2=110^2/6=2016.7Omega`

The ratio

`R_1/R_2=806.7/2016.7=0.4`