⚛️ Physics · Current Electricity · NEET & JEE

Two wires of the same material are connected in series across a 12 V source. Their lengths are 2 m and 3 m, while their cross-sectional areas are 1 mm2 and 4 mm2, respectively. What is the ratio of power dissipated in the first and second wires?

Answer: 8:3.

A 8:3
B 3:8
C 2:3
D 3:2

Correct answer: A. 8:3

Explanation: For the same material, R is proportional to L/A. Thus R1:R2 = (2/1):(3/4) = 8:3. Since the wires are in series, the same current flows through both and P = I2R, so P1:P2 = 8:3.

In series, the same current flows through both resistors; in parallel, the current splits between branches and the voltage across each resistor is the same.

Concept context

Ohm's law, resistors, Kirchhoff's laws, Wheatstone bridge, and cells.

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Two wires of the same material are connected in series across a 12 V source. Their lengths are 2 m and 3 m, while their cross-sectional areas are 1 mm<sup>2</sup> and 4 mm<sup>2</sup>, respectively. What is the ratio of power dissipated in the first and second wires?

Concept context

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