WAEC Physics 2021 Objective — Question 30
Question 30 of 50 from the West African Examinations Council (WAEC) Physics 2021 Objective paper, with the correct answer and a full explanation.
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30. An electric pressing iron is connected to the mains using an insulated wire. After some minutes, the wire becomes very hot. The heat generated in the wire can be minimized by replacing the wire with one of
- A. thinner insulation
- B. greater diameterCorrect
- C. smaller diameter
- D. thicker insulation
Explanation
A thicker wire (greater diameter) has lower resistance (R=ρl/A), reducing the heating effect (H=I²Rt) for the same current.
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