Question

With respect to electricity ,define:

(a) $watthour$, (b)$watt$, (c)$kilowatt$, (d)$kilowatthour$.

Amongst the above units, which are the units of (i) electric energy, (ii) electric power

Answer 1

Step 1:(a) Definition of $watt-hour$:

1. The rate of flow of charges in a conductor is termed electricity.
2. $watt-hour$ is the amount of electrical energy consumed by an electrical appliance of $1watt$power when it is used for $1hour$.

Step 2:(b) Definition of $watt$:

1. When $1joule$ of electric work is done in $1sec$, then electric power is said to be $1watt.$
2. $1watt=\frac{1joule}{1second}$

Step 3:(c) Definition of $kilowatt$:

1. When $1000joule$ of electric work is done in $1sec$, then electric power is said to be $1kW$
2. $1kW=1000W=1000J{s}^{-1}$

Step 4:(d) Definition of $kilowatthour$:

1. $kilowatthour$ $\left(1kWh\right)$ is defined as the amount of electrical energy consumed when an electrical appliance having a power rating of $1kilowatt$ is used for $1hour$.
2. $kilowatthour$ $\left(1kWh\right)$ is the standard commercial unit of electric energy.

Step 5:(i) Units of electric energy:

1. $watt-hour$ and $kilowatthour$ are the units of electric energy.

Step 6:(ii)Units of electric power:

1. The rate of doing electric work or the amount of electric work done in 1 sec, is termed electric power.
2. $watt$ and $kilowatt$ are the units of power.