# Relation between Stiefel-Whitney class and Chern class

A complex vector bundle of rank $n$ can be viewed as a real vector bundle of rank $2n$. From nLab, we have that the second Stiefel-Whitney class of the real vector bundle is given by the first Chern class of the complex vector bundle mod 2: $w_2=c_1$ mod $2$. Do we have similar relations for other Stiefel-Whitney classes?

Yes; see problems 14B and 14E in Milnor-Stasheff, Characteristic classes. The main point is to verify this for the top Chern class/SW class by identifying both with the Euler class (mod 2). This in turn follows by comparing the integral and mod 2 Thom classes.

• Does the problem 14B means $w_{2n}=c_n$ mod $2$? Thanks. – Xiao-Gang Wen May 8 '14 at 12:40