Question

define power and derive an expression for it​

Answer 1

Answer:

Power is defined as the rate of doing work. Alternatively, it can also be called the energy consumed by a body in unit time. It is denoted by 'P' and its SI Unit is Watt (W).

Explanation:.

Power(P) = Work Done(W) / Time taken(t)

OR

Power(P) = Energy Consumed(E) / Time taken(t)

Answer 2

Electric power is the rate at which energy is transferred to or from a part of an electric circuit. A battery can deliver energy, or a circuit element like a resistor can release energy as heat. For any circuit element, the power is equal to the voltage difference across the element multiplied by the current. By Ohm's Law, V = IR, and so there are additional forms of the electric power formula for resistors. Power is measured in units of Watts (W), where a Watt is equal to a Joule per second (1 W = 1 J/s).
General form:
electric power = voltage difference x current
P = VI
Resistors:


P = electric power (W)
V = voltage difference (V = J/C)
I = electric current (A = C/s)
R = resistance (Ω = V/A)