Question

Current density of j is flowing in a resistor of resistivity p. So
${j}^{2} p$
will be ?

Answer 1

We know that j = I/A

where I = current
A = area of cross section

j^2 = (I/A)^2
j^2p = p(I/A)^2

We know R = pl/A
p = RA/L

Putting the value in p(I/A)^2
= RA/L x (I/A)^2
= RI^2/LA

We know LA = Volume of resistor
RI^2 = Heat generated

So j^2p = RI^2/LA that is heat generated per unit volume in a resistor.

Hope This Helps You!