ITPEC FE Morning October 2023 Question 22

Source exam: ITPEC FE Morning October 2023Topic: Computer Systems & Hardware

ITPEC FE Morning October 2023 — Question 22 of 80

Power Supply Efficiency — calculate minimum input power given output and efficiency.

Formula: Input = Output / Efficiency

  • •Output = 500 W, Efficiency = 80% = 0.8
  • •Input = 500 / 0.8 = 625 W

Why not others:
- (a) 100 — meaningless; 500 × 0.2
- (b) 400 — common trap: multiplied instead of divided (500 × 0.8)
- (d) 900 — no valid derivation

Key rule: Efficiency < 100% means input is always greater than output. Use Input = Output / Efficiency, not Output × Efficiency.

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