Question
Two electric bulbs A and B are marked 220 V, 40 W and 220 V, 60 W respectively. Which one of these bulbs has higher resistance?
Solution
Given, two electrical bulbs.
Potential across first bulb, V1= 220 V
Power of first bulb, P1= 40 W
Potential across second bulb, V2 = 220 V
Power of second bulb, P2 = 60 W
Now,
P = V2/R or R = V2/P
i.e., R ∝ 1/P.
Resistance is inversely proportional to power.
Therefore, the first bulb having lesser power has higher resistance.
Potential across first bulb, V1= 220 V
Power of first bulb, P1= 40 W
Potential across second bulb, V2 = 220 V
Power of second bulb, P2 = 60 W
Now,
P = V2/R or R = V2/P
i.e., R ∝ 1/P.
Resistance is inversely proportional to power.
Therefore, the first bulb having lesser power has higher resistance.
