Real component of the wavelength of microwaves in copper

1. May 12, 2010

buttons123

I am trying to work out the real component of the wavelength of microwaves in copper. I am given n2=er=-i sigma/eo omega

where n is the refactive index
er is the relative permitivity
eo is the permitivity of free space
i = sqrt(-1)
omega is the frequency of the microwave
sigma is the conductivity of copper

I was approaching this by using n=kc/omega where k is the wavenumber and then c=f*wavelength but I am not sure about obtaining the real part of the refractive index as the whole value is multiplied by i?