NDA 2026 Physics question

A heating filament and an ideal resistor of fixed value are connected in series with a DC voltage source. After some time, the filament has reached its operating point so that the current in the circuit is steady. Which one of the following is correct ?

(A)The steady current is larger than the initial value.
(B)The steady voltage across the ideal resistor decreases as compared to its initial value.Correct
(C)Overall resistance of the circuit decreases.
(D)Power dissipation through the filament increases as compared to its initial value.

Answer: (B)

Solution

The resistance of a metal filament increases as it heats up, so the total resistance of the circuit increases

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Question ID VK-033408