Question

Kilo-watt hour is the unit of ______
A) Potential difference
B) Electric Power
C) Electric Energy
D) Charge

Answer 1

Hint: The kilowatt-hour is used as a unit to represent the standard unit of energy. It is used to determine how much energy is used by electrical utilities.

Complete step by step answer:
Step I:
Kilo-watt hour means the number of kilowatts used in a given time. It is the standard unit to represent electric energy.
Electric energy is defined as the energy generated by the movement of electrons from one point to another. Since the electrons are moving, they will have kinetic as well as potential energy. Due to the movement of electrons or charged particles, an electric current is produced.
Step II:
Kilo-watt hour is represented by the symbol $kWh$. It is used to calculate how much energy is required to run an electric appliance and how much it will cost.
Step III:
kWh can also be expressed as the standard unit of energy in S.I. units. It is represented by using symbol ‘$J$’. Relation between $kWh$ and $J$ is
\[1kWh = 1kW \times 1hour\]---(i)
\[1hour = 3600\sec onds\]
Substituting this value in equation (i),
\[1kWh = 1000Watt \times 3600\sec onds\]
\[1kWh = 3.6 \times {10^6}J\]

$\therefore$ Kilo-watt hour is the unit of electric energy. Hence, option (C) is correct.

Note:
Sometimes there can be a confusion between kilo-watt and kilo-watt hour. It looks like they are similar but in actuality, they are different. Though they are interrelated and both are units of measurement, there is a difference between them . Kilo-watt hour (kWh) reflects the total amount of electricity used, but kilo-watt represents the rate of electricity used. They are inter convertible. To convert the power in watts to kWh. The formula used is
\[kWh = \dfrac{{Watt \times hours}}{{1000}}\]