Answer
A photon behaves like a wave when it is traveling from one place to another. It behaves like a particle when it is emitted by an atom, or absorbed by a piece of film or a detector.
Work Step by Step
This is explained on page 590.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.