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MDCAT
Physics
2021

Physics · Current Electricity

Work through this past-paper style MCQ, then read the full explanation. Practice more physics questions on mMCQ with adaptive practice and topic analytics.

Question

An electric iron is 20V & 500W . The unit consumed by it (in kJ) in using it for 24 hours will be:

Options
  • A

    12 units

  • B

    24 units

  • C

    5 units

  • D

    1100 units

Explanation

Power = energy/time

500 = E/24

E = 500 x 24 

= 12,000 J

Here, the power of the electric iron is given as 500 watts (or 0.5 kilowatts) and the time is 24 hours. So, the energy consumed would be: 0.5 kW x 24 hours = 12 kWh (kilowatt-hours). In terms of units, 1 kWh is equal to 1 unit. Thus, the iron would use 12 units of electricity in 24 hours.

Incorrect as per formula

Incorrect as per formula

Incorrect as per formula

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Tagged under Physics · Current Electricity · 2021