Practice problem

Commutative Algebra

Let $\phi\colon A\to B$ be a ring homomorphism. If $\wp$ is a prime ideal of $A$ , describe $\operatorname{Spec}(B_\wp/\wp B_\wp)$ , the set of prime ideals of $B_\wp/\wp B_\wp = B\otimes_A (A_\wp/\wp A_\wp).$

(Source: Cf. Qing Liu, Chapter 3, Proposition 1.16)