Energy, Power And Heating Effect Of The Current

Current Electricity of Class 12


When a constant current I flows for time t from a source of  emf E, then the amount of charge that flows in time t is Q = It.  Electrical energy delivered W = Q.V = VIt

Thus, power given to the circuit = W/t = VI or  V2/R   or I2R

In the circuit, we can write,  E. I = I2R + I2 r, 

where EI is the rate at which chemical energy is converted to electrical energy, I2R is power supplied to the external resistance R and I2r is the power dissipated in the internal resistance of the battery.

An electrical current flowing through, a conductor produces heat in it. This is known as Joule's effect. The heat developed in Joules is given by H = I2.R.t,  where I = current in Ampere, and R = resistance in ohms, t = time in seconds.

The equation H = I2Rt is also known as Joule’s law of heating.

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