Advertisements
Advertisements
Question
An electric heater of power 3 kW is used for 10 h. How much energy does it consume? Express your answer in
- kWh,
- joule.
Advertisements
Solution
Given:
Power of Heat P = 3 kW
Time t = 10 h.
(i) Energy consumed = power × time
Energy = 3 kW × 10 h = 30 kWh
(ii) 1 kilowatt hour (kWh) = 3.6 × 106 J
30 kWh = 30 × 3.6 × 106 J
= 108 × 106 J
= `108/100 xx 100 xx 10^6` J
= 1.08 × 108 J
APPEARS IN
RELATED QUESTIONS
1 H.P. is equal to
It takes 20 s for a girl A to climb up the stairs while girl B takes 15 s for the same job. Compare the power spent by then.
Differentiate between watt and watt hour.
What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop?.
A bullet of mass 20 g strikes a pendulum of mass 5 kg. The centre of mass of the pendulum rises a vertical distance of 10 cm. If the bullet gets embedded into the pendulum, calculate its initial speed.
An engine pumps up 200 kg of water through a height of 20 m in 10 seconds. If the efficiency of the engine is 80%. Calculate the power of the engine.
Name the quantity which is measured in kW.
Name the quantity which is measured in Wh.
Name the quantity which is measured in eV.
At any instant of time t, the displacement of any particle is given by 2t – 1 (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit):
