Question

How the units of power and voltage are represented?
$\text{A}\text{. W, V}$
$\text{B}\text{. A, V}$
$\text{C}\text{. W, }\Omega \text{ }$
$\text{D}\text{. V, }\Omega \text{ }$

Answer 1

Hint: To perform any work on an object, energy is required. The rate at which energy is used to perform the work is known as power. Voltage, also known as electric potential difference, is defined as the work to be done on a unit positive charge to move a test charge from one point to another in an electric field.

Complete answer:
Work done by an electromotive force to bring a unit positive charge from point A to B is known as potential difference or voltage. Its SI unit is Volt ($V$).
Voltage can be given by:
$\Delta V=V_B-V_A$
Power is the rate of doing work. Every electric appliance uses electrical energy at different rates. Power rating of an appliance tells us the energy it uses per second. The mathematical relation for power is:
$P=\dfrac{\Delta W}{t}$
SI unit of Power is watt ($W$)

So the correct option is A.

Additional Information:
To move a charge from one point to another in an electric field, work is done by external forces. This work done is stored as potential energy. At every point, in an electric field, a charge $q$ possesses some electrostatic potential energy. When charge is moved, this work done increases its potential energy by an amount equal to potential energy difference between those points.
If a charge is moved from point A to B in an electric field, the potential energy difference is given by:
$\Delta U = U_B -U_A = W_{AB}$
The work done by external force in bringing a unit positive charge from infinity to that point against an electric field is known as electrostatic potential at that point. The SI unit of electrostatic potential is Volt or $V$.
$1\text{ Watt = 1 J}{{\text{s}}^{-1}}$

Note:
Questions related to SI Units and CGS Units are very common in physics exams, so students must try to learn SI units.
Students should also learn to derive units of physical quantities using dimensional formulas.