Question

Some electric bulbs are connected in series across a 220 V supply in a room. If one bulb is fused then remaining bulbs are connected again in series across the same supply. The illumination in the room will

• A. Increase
• B. Decrease
• C. Remains the same
• D. Not continuous

Answer 1

Answer: (A)

Increase

Answer 2

$P = \frac{V^{2}}{R}$ ⇒⇒ $P \propto \frac{1}{R}$ (V - constant)

∴ When one bulb will fuse out resistance of the series combination will be reduced.

Hence from $P_{Consumed} \propto \frac{1}{R}$ illumination will increase.