Question

A heater is marked 1000 W. The energy consumed by it in 10 hours is
A. 10 J
B. 10 KJ
C. 10 kWh
D. 100 KJ

Answer 1

We have to obtain the amount of energy consumption in kilowatt hour so in the solution we will be using the expression of energy which gives us the relation between energy consumed by the apparatus, time period of operation and power of the apparatus.

Complete step by step answer:
Given:
The marked power of the heater is P=1000 W.
The time period of energy consumption is t=10 hrs.
We know that the expression of energy E in terms of power P is given by,
$E = P \times t$
We will now substitute P=1000 W, t=10 hrs to find the value of power P.
$\Rightarrow E = 1000\;{\rm{W}} \times 10\;{\rm{h}}$
$\Rightarrow E = 1000\;{\rm{W}} \times \dfrac{{1\;{\rm{KW}}}}{{1000\;{\rm{W}}}} \times 10\;{\rm{h}}$
$\Rightarrow E = 1\;{\rm{KW}} \times 10\;{\rm{h}}$
$\Rightarrow E = 10\;{\rm{KWh}}$

Therefore, the energy consumed in 10 hours is 10 KWh and the correct option is (C).

Additional Information:
Power is a unit to measure the work we have done. It can be explained in many ways. Because the work is done in a different unit. It can be explained in terms of voltage, energy, torque, etc. The rate of doing work is called Power. Power is the measure of the amount of work we did in a given limit. In other words, power can be defined as the amount of work we did in converting the energy from one form into another in a given time.

Note: Do not forget to convert the obtained energy consumption from Watt hour to kilowatt hour as the final answer is asked in kilowatt hour. Also, take care of the value of time period because it has to be substituted for 10 hours and not 10 seconds.