Question

why drude model failed to explain seebeck effect

Answer 1

This question has a long answer. First of all, Let's see what is seebeck effect. Electrons from higher temperature side will have higher speed with net motion from high temperature to low temperature. It means electrons will accumulate on low temperature side and will produce an electric field that will further attract more electrons. This is called as seebeck effect.

E = Q? T where Q is thermal power

where Q = - (1 /3ne )C_v

where C_v = 3/2nk_b where k_b is boltzmann constant

Now, drude model calculated value of Q as around - 0.43e-4 V/K

However, the observed value of Q is approximately 100 times smaller than this. This difference arise because drude estimated the value of C_v more by a factor of 100 which makes drude model inefficient for seebeck effect.

Moreover, sometimes, we also get Q value as positive which drude model never explained.