Question

two electric bulbs are rated as220V-100W and 220V-60W.which these has greater resistance and why?

Answer 1

For first bulb

Potential difference = 220 V

Power supplied = 100 W

We know that P = V²/R

So, 100 = 220 * 220 / R

R = 220*220/100 = 484 ohm

For second bulb

Potential difference = 220 V

Power supplied = 60 W

We know that P = V²/R

R = 220*220/60

R = 806.6667 ohms.

Hence, from calculation the second bulb has more resistance.

More is the power, less is the resistance and conversely less is the power, more is the resistance.

This is the reason.

Hope this helps you.