Question

What is the commercial unit of energy? Establish the relationship between this unit and the SI unit of energy? Or Define one kilowatt hour. Express it in joules.

Answer 1

Explanation

1. The commercial unit of electric energy is kilowatt-hour $\left(KWh\right)$ or Board of Trade $\left(B.O.T.\right)$ unit.
2. It is defined on the electric energy consumed by an appliance of power$1000watt$ in one hour.
3. $$\begin{gathered} \Rightarrow 1kWh=1kWx1h=1000Wx1h \\ \Rightarrow 1kWh=1000Js¹\times 3600s \\ \Rightarrow 1kWh=3600000J=3.6\times {10}^{6}J \end{gathered}$$
4. The electrical energy used in households, industries and commercial establishments is expressed in kilowatt hour.
5. The energy used is expressed in terms of 'units' in our monthly bills.
6. Here $1$ unit means $1$ kilowatt hour.