# Formula developing

1. May 22, 2010

### nhrock3

$$0=q\mu \bar{n}E-qD_e\frac{d\bar{n}}{dx}\\$$
$$\frac{{}D_e\frac{d\bar{n}}{dx}}{\mu \bar{n}}=E\\$$
$$v=-\int_{x_n}^{x_p}Edx=-\int_{x_n}^{x_p}\frac{{}D_e\frac{d\bar{n}}{dx}}{\mu \bar{n}}dx=-\int_{x_n}^{x_p}\frac{{}D_e\d\bar{dn}}{\mu \bar{n}}\\$$

they say some thing about einshtein
why Dn/$$\mu$$=kt/q??
so we see that dx and 1/dx eliminate each other so its not and integral anymore
we dont have dx

and i dont know how from this point they get??
$$\frac{kt}{q}\ln p |^{x_p}_{x_t}=\frac{kt}{q}\ln\frac{{}{N_AN_D}}{n_i^2}$$
and
where the put x_p and x_n in the integral
wht is our variable
??