It is not a strange in physics to define what ‘power’ is. The power is defined to as the energy converted or the rate at which the work is performed.
Consider ΔW as the work done and Δt as the time at which the work is done, then the average power can be calculated as
pavg= ΔW/ Δt
The average power or pavg can also be called as just ‘power’. So the average power is the average of work done in unit time. The limiting value of average power is called as the instantaneous power. The work done to produce the constant power under a unit time can be calculated by using the equation
Power has got different units depending on the situation it is being used. The SI unit is watt (W). It can be joules per second also. Other units are the ergs per seconds or the horsepower.
In mechanics the work done is defined using the equation
Where F is the force and Δd is the displacement. It is the force acting on a object and the displacement of the object.
It is the instantaneous electrical power of a component and is written as
P(t)= I(t). V(t)
Where P(t) is denoted as power in watts or in joules per second. I(t) is denoted as the current in amperes and V(t) is denoted as the potential difference across the components in volts. In the case of a resistor the power is written to as
Where R="V/I" which is the resistance in ohms.
In optics the power is defined to as the average rate of energy transport in a electromagnetic radiation and it is measured in watts. The term power is also used to define the ability of a lens to focus on to light and it can also be defined as the focal length of the lens.