Question

What is the value of 1kWh equal to?
A.)$\text{3}\text{.6 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{6}}}\text{MJ}$
B.)$\text{3}\text{.6 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{5}}}\text{MJ}$
C.)$\text{3}\text{.6 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{2}}}\text{MJ}$
D.)$\text{3}\text{.6MJ}$

Answer 1

Hint: Convert the unit kWh into the SI units (MKS system). Recall that 1 hour=3600 seconds.

Complete step by step answer:

1 kWh or kiloWatt-hour is a unit for the measurement of energy. It is extensively used in electrical appliances and by the state body providing electricity to residential and commercial areas.
The word Kilo stands for 1000 in the metric system.
Watt is a unit of power that is equal to the consumption or production of 1 Joule of energy per second by a body.
$\text{1Watt=}\dfrac{\text{1Joule}}{\text{1Second}}$
$\text{1hour=3600seconds}$
Now, with this information, we will now convert 1 kWh into the proper MKS units. Converting 1kWh into the proper SI units gives:

$\text{1kWh=1000 }\!\!\times\!\!\text{ (1J}{{\text{s}}^{\text{-1}}}\text{) }\!\!\times\!\!\text{ (3600s)}$
\[\therefore \text{1kWh=3}\text{.600000J}\]
$\therefore \text{1kWh=3}\text{.6 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{6}}}\text{J}$
$\therefore \text{1kWh=3}\text{.6MJ}$
Where M stands for mega or 10⁶ in the metric system.
Hence, the correct answer is D) 3.6MJ

Additional information:
Horsepower is a unit for power, where 1Watt =746 hp approximately. Horsepower is often used in the automotive industry to measure the output of an engine.

The state electricity board measures the units of electric energy used by a residence or commercial establishment in terms of kWh. They consider 1 unit of electrical energy as 1 kWh. The number of units consumed is shown on the electric meter of the house. A man from the electric supply board comes and notes down the number to send it to the supply board, so that they can charge you accordingly.

Note: Students may not notice the MJ unit or mega joule and may mark the correct option as A) 3.6× 10⁶ MJ. However, this is incorrect since the M in MJ already takes care of the 10⁶ factor.