Two wires of the same material have the same length but their radii are in the ratio of 5:3. They are combined in series, where the resistance of the thicker wire is 12 ohms. Calculate the total resistance of the combination.(a) 40(b) 12(c) 32(d) 20I have been asked this question during an interview.I need to ask this question from Combination of Resistors in chapter Current Electricity of Physics – Class 12

Two wires of the same material have the same length but their radii ar

1.	Two wires of the same material have the same length but their radii are in the ratio of 5:3. They are combined in series, where the resistance of the thicker wire is 12 ohms. Calculate the total resistance of the combination.(a) 40(b) 12(c) 32(d) 20I have been asked this question during an interview.I need to ask this question from Combination of Resistors in chapter Current Electricity of Physics – Class 12
Answer» Correct answer is (c) 32 The explanation is: The given ratio of radii = 5:3; \(\frac {R2}{R1} = \frac {5}{3}\) → R2 = \((\frac {5}{3})\) R1 R1 = 12 ohms (given); R2 = \(( \frac {5}{3} )\) × 12 = 20 ohms. So, R1 = 12 ohms and R2 = 20 ohms Therefore, total resistance (R) = R1 + R2 (since they are COMBINED in series) = 12 + 20 = 32 ohms Thus, the total resistance of the combination is 32 ohms.

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