Question

One unit of electric energy is equal to

• A. One kilowatt-hour
• B. One watt-hour
• C. $100$ joules
• D. None of the above

Answer 1

The correct option is A

One kilowatt-hour

The explanation for the Correct answer:

In the case of option A.

1. A kilowatt-hour is a unit of energy equivalent to one kilowatt $\left(1kW\right)$ of power expended for one hour $\left(1h\right)$ of time.
2. The kilowatt-hour is actually not a standard unit in any formal system of units, but it is commonly used in electrical applications everywhere.
3. The reason that this unit is used to measure your usage rather than kilowatts on its own is that $kWh$ is a measurement of absolute power consumed over a time interval.
4. Thus, the correct option is option A.

The explanation for incorrect answers:

In case of option B.

1. One watt-hour is a small unit compared to a kilowatt-hour.
2. In the case of household cases, it is not convenient to take a small unit for energy consumption.
3. Thus, option B is an incorrect option.

In case of option C.

1. In the case of electric energy, joules are not used singularly.
2. There must always be a time rate of energy.
3. Thus, option C is an incorrect option.

In case of option D.

1. It is an absurd option as option A is correct.
2. Thus, option D is an incorrect option.

Thus, the correct option is option A.