Explaining I^2R=J_c/σ Relationship

[lavster]

can someone explain how these two are equal:

$$I^2 R = J_c \cdot \frac{J_c}{\sigma}$$

where I is the current, R is resistance, J_c is conduction current density, and $$\sigma$$ is the conductivity.

thanks

 

[nasu]

They don't seem to be equal so there is nothing to explain.
You can just look at the units. The right hand side is power density (W/m^3) and the left hand side is just power (Watt)

 

[gomunkul51]

I=[A]
R=[Ohm]
J=[A/m^2]
sigma=[1/(Ohm*m)]

you have a problem there with units :)