Question

Two electric bulbs, one of 200 volt - 40 watt and the other of 200 volt - 100 watt are connected in a house wiring circuit

• A. 1) they have equal currents through them
• B. 2)the resistance of the filaments in both the bulbs issame
• C. 3) the resistance of the filament in 40 watt bulb is more than the resistance in 100 watt bulb
• D. 4) the resistaince of the filament in 100 watt bulb is more than the resistance in 400 watt

Answer 1

Answer: (C)

3) the resistance of the filament in 40 watt bulb is more than the resistance in 100 watt bulb

In house wiring circuit, the connections are parallel.

both bulbs have same voltage.

$\Rightarrow P_1=\frac{V^2}{R_1};P_2=\frac{V^2}{R_2}$

$\Rightarrow R_1=\frac{V^2}{P_1};R_2=\frac{V^2}{P_2}$

$\Rightarrow R\propto \frac{1}{P}$

since. $P_2>P_1$ [40<100]

$\Rightarrow R_1>R_2$