NCERT Solutions for Class 9 Science Chapter 11
Important NCERT Questions
Work and Energy
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Exercises Questions
Page No-159
Questions No-20
Find the energy in kW h consumed in 10 hours by four devices of power 500 W each.
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Energy = Power x Time
Given that each device has a power of 500 W and the time duration is 10 hours, let’s calculate the total energy consumed by all four devices:
Total power of four devices = 4 x 500 W = 2000 W
Time = 10 hours
Now, to find the energy consumed:
Energy = Total Power x Time
Energy = 2000 W x 10 h
Let’s calculate:
Energy = 20,000 Wh
To convert watt-hours (Wh) to kilowatt-hours (kWh), we divide by 1000:
Energy = (20,000 Wh)/(1000) = 20 kWh
Therefore, the total energy consumed by the four devices in 10 hours is 20 kilowatt-hours (kWh).