# Very small question about the Clausius-Mosotti derivation.

1. Jan 12, 2015

### Coffee_

This is the solution to an exercise in Griffiths where one has to derive the Clausius Mosotti relationship:

http://physicspages.com/2012/11/28/relation-between-polarizability-and-susceptibility/

I have one small question about the use of the word ''applied'' at the beginning when defining $\vec{E}$. As $\vec{E}$ is used it seems to me that it is supposed to represent the TOTAL macroscopic field including both the externally applied field and the macroscopic field caused by polarization.

So basically, I'm asking what is meant by applied here because it seems that they mean that $\vec{E}$ is the externally applied field. If this is so their use of that field seems not too correct then.

2. Jan 12, 2015

### TSny

You are right. E should be interpreted as the total macroscopic field, not just the externally applied field.