Question

Write S.I unit of electric power.

Answer 1

Hint: Electric power is the electric energy consumed per unit time. It is denoted as ‘P’ and given by the equation $P=V\times I$. It’s S.I. unit is similar to that of electrical energy. Different expressions can be obtained by using coulomb's law and ohm’s law.

Complete step-by-step answer:
Electric power can also be defined as electric energy or energy consumed per unit time. It is the rate of doing work and represented as ‘P’. The equation for electric power can be written as,
 $P=V\times I$
Where, ‘V’ is the electric potential in volts
      ‘I’ is the current in amperes.
The equation can also be written by substituting $I=\dfrac { Q }{ t }$, which becomes
$P=\dfrac { VQ }{ t }$
Where, ‘Q’ is the electric charges given in coulombs
       ‘t’ is the time taken in seconds
The electric power in watts is the electric current of charge ‘Q’ passing through potential difference of voltage ‘V’ for every ‘t’ seconds.
In accordance with resistive circuits, Joule’s law can be used with Ohm’s law to provide another expression for power. Ohm’s law is given by $V=I\times R$. On substituting in electric power equation, it becomes
$P=IV={ I }^{ 2 }R=\dfrac { { V }^{ 2 } }{ R }$
Where, ‘R’ is the electric resistance in ohms.
The power consumed in a circuit is said to be one watt, if one ampere current flows through the circuit with 1volt potential difference across the circuit.
The S.I unit of power is watt which was named after James Watt.
$1W=kg{{m}^{2}{{s}^{-3}}}$
The bigger unit for electric power is kilowatt i.e., 1kW=1000W. Kilowatt-hour is used as a billing unit for energy.

Note: The electric power is of two types. They are the AC power and DC power. The classification depends upon the nature of the electric current. The DC power is the product of voltage and current whereas, AC power is the product of rms value of voltage and current.