JAMB Physics 2008 Objective — Question 43
Question 43 of 50 from the Joint Admissions and Matriculation Board (JAMB) Physics 2008 Objective paper, with the correct answer and a full explanation.
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43. A step-down transformer has an output of 50W and efficiency of 80%. If the mains supply voltage is 200V, calculate the primary current of the transformer.
- A. 0.31ACorrect
- B. 3.20A
- C. 3.40A
- D. 5.00A
Explanation
Efficiency = output power/input power. Input power = 50/0.8 = 62.5W. Primary current = 62.5/200 = 0.31A.
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