Question

Electrical work done per unit time is:
A. Electrical Energy
B. Electrical Current
C. Electrical Power
D. Electrical Circuit

Answer 1

Hint: In our house, why are we paying for electricity? We are paying for the work done by the electrons per unit time (or day) to transfer the electricity through our house. Which is monitored by an electric meter, which tells this whole activity as power consumed a day.

Completer step by step answer:
Suppose we take a closed circuit, with a battery. When we switch on the key, electrons start to move throughout the circuit, where does this energy come from? It is the battery which gives the energy to run the electron from negative potential or lower potential to positive potential or high potential. This is known as work done by electron or simply electric work.

And work done for a particular time or per unit time is called Power (P).
SI unit of Power is Watt (W) named after Physicist James Watt.

One Watt is the Power consumed by a device that carries one Ampere of current when operated at potential difference of one volt.
Mathematically,

\[Power(P)=\dfrac{Work(W)}{Time(T)}\]

Thus we can say, the rate of doing work is called Power.

Answer is option (C). Electrical Power

Additional Information:
The unit of watt is very small. In actual practice we use larger units called ‘kilowatt’.
1 KW = 1000W (K means kilo)
1 MW = \[{{10}^{6}}\]W ( M means Mega)
1 GW = \[{{10}^{9}}\] W ( G means Giga)

Power consumed in one hour is called 1KWh or 1 unit.

\[\begin{align}
  & 1KWh=1000\times 1hr \\
 & 1KWh=1000\times 60\times 60 \\
 & 1KWh=1000\times 3600 \\
 & 1KWh=3.6\times {{10}^{6}}Joule \\
\end{align}\]

Note: In physics there are many formulas, and each one of them can be derived if you just remember only one form of it.

For example formula of power is:

\[\begin{align}
  & P=\dfrac{Work}{Time} \\
 & P=\dfrac{force\times displacement}{Time} \\
 & P=force\times velocity \\
 & P=F.v \\
\end{align}\]

Another form is:

\[\begin{align}
  & P=\dfrac{Work}{Time} \\
 & P=\dfrac{W}{T} \\
 & P=\dfrac{qW}{qT} \\
 & \dfrac{q}{T}=I \\
 & \dfrac{W}{q}=V \\
 & P=VI \\
\end{align}\]