Advertisements
Advertisements
प्रश्न
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
उत्तर
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
संबंधित प्रश्न
The S.I. unit of power is ..........
1 H.P. = .........
Differentiate between watt and watt hour.
Choose one or more correct alternatives.
Power is a measure of the ______.
- The rapidity with which work is done.
- Amount of energy required to perform the work.
- The slowness with which work is performed.
- Length of time.
A wind-powered generator converts wind energy into electric energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. For wind speed v, the electrical power output will be proportional to ______
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.
Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g = 10m/s2)
A man is throwing bricks of mass 2 kg onto a floor from a height of 2 m. Bricks reach the floor at a speed `2sqrt(10)` m/s. Man throws 10 bricks in a minute. If the power of man is W watt then `3/10` W is equal to ______ W.
Name the quantity which is measured in kW.
