Question

State joules law of heating

Answer 1

Consider a current I flows through a resistor of resistance R on applying a potential difference V across it.

Let charge Q flows though the resistor in time t.Them the work done in moving charge Q is

                                                     W=VQ .............(i)

We know that                        I=Q  or Q=It
                                                     t
Thus,From euqation (i),          W=VIt

This work done is equal to the energy supplied by the source in time t.This energy gets dissipated in the form of heat in the resistor.Therefore,the heat produced in a resistor is

                                                            H=VIt
By using Ohm's Law,V=IR,we get  H=I²Rt

This implies that the heat produced in a resistor is

(i)directly proportional to the square of current for a given resistance in a given time.
 That is                                H∝ I²

(ii)directly proportional to the resiastance for a given current in a given time.
That is                                H∝R

(iii)directly proportional to the time for which current flows through the resistor.

That is                                 H∝ I


This is known as Joule's Law of Heating

Answer 2

Answer:

joules law states that , the heat produced in a conductor is directly proportional to the square of the current flowoing in the conductor , to the time taken by the current to flow , to the resistance

H x I2

   x R

   x t

H=I2Rt