WAEC Physics 2023 Objective — Question 30
Question 30 of 50 from the West African Examinations Council (WAEC) Physics 2023 Objective paper, with the correct answer and a full explanation.
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A cell of emf 2 V has an internal resistance of 0.5 Ω. A current of 0.4 A passes through an external resistor, P. Determine the resistance of P.
- A. 5.0 Ω
- B. 4.5 ΩCorrect
- C. 4.0 Ω
- D. 1.0 Ω
Explanation
Using I=E/(R+r): 0.4=2/(R+0.5) → (R+0.5)×0.4=2 → R+0.5=5 → R=4.5 Ω.
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