The following four wires are made of the same material and are at the same temperature. Which one of them has highest electrical resistance?
Correct answer: C. Length = 50 cm, diameter = 0.5 mm
- A. Length = 100 cm, diameter = 1 mm
- B. Length = 200 cm, diameter = 2 mm
- C. Length = 50 cm, diameter = 0.5 mm
- D. Length = 300 cm, diameter = 3 mm
Explanation
Resistance is given by R = ρL/A, where A is proportional to the diameter squared. To maximise resistance, we need the largest ratio of length to area (L/d²). Calculating this ratio for each option shows that the wire with L=50cm and d=0.5mm has the highest resistance.
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Steady current relates charge flow to potential difference, resistance and resistivity, including how temperature changes a conductor's resistance. Sources with internal resistance have terminal voltage below their emf when delivering current, and maximum power output occurs under a specific load condition rather than at zero resistance.
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