Question

In the circuit diagram, all the bulbs are identical. Which bulb will be the brightest?

• A. A
• B. B
• C. C
• D. D

Answer 1

Answer: (C)

As all bulbs are identical and the power (related to brightness) is given as $P=I^{2}R$, so the resistor with the most current will be brightest. As bulb $C$ has the same current as that through the battery, while the branches with bulbs $A,B$ and $D$ are in parallel and have the total current split between the branches, the current through bulb $C$ is greatest.