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A step-down transformer has a power output of 50 W and efficiency of 80%. if...

Physics
JAMB 2008

A step-down transformer has a power output of 50 W and efficiency of 80%. if the mains supply voltage is 200 v, calculate the primary current of the transformer.

  • A. 0.31 A
  • B. 3.20 A
  • C. 3.40 A
  • D. 5.00 A
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Correct Answer: Option A
Explanation

Efficiency = (power output)/power input x 100%
= 1s VS x 100% 1p
Vp
∴ (80)/100 = (50)/IP x 200
I P = (50 x 100)/80 x 200 = 0.3125 A

There is an explanation video available below.


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Explanation Video

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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC offline past questions - with all answers and explanations in one app - Download for free
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts