Question

Derive an expression for joules law of heating< >please!!!.

Answer 1

Current (I)=Charge (q)Time (t)Current (I)=Charge (q)Time (t)

q = It……(i)q = It……(i)

If the potential difference between A and B is V. Then,

V = IR……(ii)V = IR……(ii)

Let ‘W’ be the amount of work done to move ‘q’ amount of charge through the resistance.

 So, Electric potential(V)=Workdone (W)q  So, Electric potential(V)=Workdone (W)q 

 or, W = qV or, W = qV

 W=VIt……(ii) W=VIt……(ii)

Now, from equation (i) and (ii)  and (iii),

W = It.IRW = It.IR

or, W = I2 RTor, W = I2 RT

Heat produced, H= RT  joule

In CGS system,

H=I2RTJCal

Answer 2

H directly proportional to I^2Rt
H=KI^2Rt
but K=1
H=I^2Rt