Question

Two bulbs A and B are connected to a 220V main supply. The maximum current that can flow through A and B is 0.5A and 1.2A respectively. The effective resistance of two bulbs in series and in parallel is $280\Omega$ and $60\Omega$ respectively. Which of the two bulbs will fuse when connected in series.

• A. A
• B. B
• C. Both will fuse together
• D. Both will fuse one after another spontaneously

Answer 1

The correct option is A A

Series combination :

Equivalent resistance $R_s=280\Omega$

Current flowing in series connection $I_s=\frac{V}{I_s}=\frac{220}{280}=0.79$ A

But safe current limit through bulb A and B is $0.5A$ and $1.2A$. Hence bulb A will fuse when connected in series.