# ohmic heating in a conductor

by smcdan32
Tags: electrodynamics, ohmic, plane wave
 P: 4 question For a plane wave of the form E(z,t)=Ee^i(kz-wt) and B(z,t)=Ee^(-kz)*e^i(kz-wt) write down the time-averaged ohmic heating loss per unit volume for any z. 2. Relevant equations J=$$\sigma$$E Maxwell's equations for linear media 3. The attempt at a solution not sure where to start, i need a nudge
 P: 2,070 You know E, and you gave us the equation for J, so you know J. Do you know how to find the Ohmic heating, given J and E?
 P: 4 yea i figured it out. you take the dot product of J and E.
P: 4

## ohmic heating in a conductor

ok now i have Re($$\sigma$$) ((Ee^(-kz)e^i(kz-$$\omega$$t))^2)/2

is this right? do i need to simplify if im going to integrate with respect to z?
 P: 2,070 Careful with the Re(). Remember Re(A) Re(B) is not equal to Re(AB) since there are cross terms. Here it looks like you assumed Re(E^2) = (Re(E))^2, which it's not.
 P: 4 so is what i have already wrong?

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