Question

After an incandescent lamp is turned on, the temperature of its filament rapidly increases from room temperature to its operating temperature. As the temperature of the filament increases, what happens to the resistance of the filament and the current through the filament?
(1) The resistance increases and the current decreases.
(2) The resistance increases and the current increases.
(3) The resistance decreases and the current decreases.
(4) The resistance decreases and the current increases

Answer 1

I think the correct answer from the choices listed above is option 1. As the temperature of the filament increases, the resistance of the filament and the current through the filament would be that the  resistance increases and the current decreases. Hope this answers the question.

Answer 2

Answer: (1) The resistance increases and the current decreases.

Explanation:  

When the temperature of the filament increases, the vibrational energy of the constituent atoms increases which leads to increase in inter-atomic collision. Thus, the resistance would increase. The increases in resistance would obstruct the flow of charges more leading to decrease in the value of the current.

Hence, when the temperature of the filament increase, the resistance increases and current decreases.