Question

Three bulbs A, B and C rated 40 W, 60 W and 100 W, respectively, are connected in parallel to a voltage source of 220 V. The bulb that glows with maximum brightness is?

• A. all bulbs will glow with equal brightness
• B. bulb C
• C. bulb A
• D. bulb B

Answer 1

Answer:

B. bulb C

• When bulbs are connected in parallel, the voltage across each bulb is the same.

• Power (P) is given by P = V²/R, where V is the voltage and R is the resistance.

• Since the voltage is constant, the bulb with the lowest resistance will have the highest power and thus glow with maximum brightness.

• Resistance (R) is inversely proportional to power (R = V²/P).

• Therefore, the bulb with the highest wattage(100W) will have the lowest resistance and hence glow with the maximum brightness.

• This is bulb C.