Why do P waves change direction while passing through the outer core?

Correct answer: Due to refraction

When P waves enter the outer core, their speed changes because the properties of the medium change sharply. This bends their path, and the bending is called refraction. Reflection would mean that the waves bounce back, whereas here their direction mainly changes while travelling through the new medium. Exam tip: P waves can travel through the liquid outer core, but their speed and direction change.