Light bulb A is rated at 60 W and light bulb B is rated at 100 W. Both are designed to operate at 110 V. Which statement is correct?
A) The 60 W bulb has a greater resistance and greater current than the 100 W bulb.
B) The 60 W bulb has a greater resistance and smaller current than the 100 W bulb.
C) The 60 W bulb has a smaller resistance and smaller current than the 100 W bulb.
D) The 60 W bulb has a smaller resistance and greater current than the 100 W bulb.
E) We need to know the resistivities of the filaments to answer this question.

Question

Quizplus · Accepted Answer

The power of the bulb is given by P=V^2/R, where P is power, V is voltage and R is resistance. As both bulbs are designed to operate at the same voltage, the bulb with a higher power rating (100 W) must have a lower resistance than the bulb with a lower power rating (60 W). Therefore, option B is correct as it states that the 60 W bulb has a greater resistance and smaller current than the 100 W bulb. Option A and D are incorrect because they suggest that the 60 W bulb has a greater current, which is not possible as the higher power 100 W bulb would draw more current. Option C and E are also incorrect as they do not take into account the power rating of the bulbs.

Light Bulb a Is Rated at 60 W and Light