efficiency in physics

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Efficiency of a machine is measured by

Efficiency of a machine is measured by
  • A. (Wasted Energy Output ⁄ Energy Input) × 100 %
  • B. (Energy Input ⁄ Wasted Energy Output) × 100 %
  • C. (Useful Energy Output ⁄ Energy Input) × 100 %
  • D. (Energy Input ⁄ Useful Energy Output) × 100 %
  • Correct Answer: Option C

Formula for efficiency is

Formula for efficiency is
  • A. (energy input / energy output) × 100
  • B. (energy input / energy output) × 100
  • C. (useful energy input / energy output) × 100
  • D. (useful energy output / total energy input) × 100
  • Correct Answer: Option D

A car uses total energy of 2500 J and output is 750 J. efficiency of car is

A car uses total energy of 2500 J and output is 750 J. efficiency of car is
  • A. 50%
  • B. 30%
  • C. 25%
  • D. 80%
  • Correct Answer: Option B

In a typical power station, amid a series of energy transfers and conversions, about 70% of energy input gets wasted in form of thermal energy, efficiency of such a power station is about

In a typical power station, amid a series of energy transfers and conversions, about 70% of energy input gets wasted in form of thermal energy, efficiency of such a power station is about
  • A. 0.3
  • B. 0.4
  • C. 0.7
  • D. 1
  • Correct Answer: Option A

Output of a truck is 4500 J and its efficiency is 50%, input energy provided to truck is

Output of a truck is 4500 J and its efficiency is 50%, input energy provided to truck is
  • A. 5000 J
  • B. 900 J
  • C. 9000 J
  • D. 500 J
  • Correct Answer: Option C