A light bulb with a tungsten filament is attached to a source of variable voltage.As the voltage is increased on the bulb,
A)the bulb's resistance decreases.
B)the bulb's resistance increases.
C)the current in the bulb decreases.
D)the power dissipated remains constant.

Question

Quizplus · Accepted Answer

As the voltage is increased on the bulb, the temperature of the tungsten filament increases, which causes an increase in the resistance of the bulb. This ultimately leads to an increase in the power dissipated as well. Ohm's law states that I = V/R, so if the resistance increases with the voltage, the current will decrease. Therefore, choice B is the best answer. Choice A is incorrect because the resistance of the bulb increases, not decreases. Choice C is also incorrect because when the resistance increases, the current in the bulb decreases, not increases. Choice D is also incorrect because the power dissipated will increase as the voltage and resistance increase.

A Light Bulb with a Tungsten Filament Is Attached to a Source