Conceptual Physics (12th Edition)

Published by Addison-Wesley
ISBN 10: 0321909100
ISBN 13: 978-0-32190-910-7

Chapter 31 - Think and Explain: 34


Frequency determines the KE of ejected electrons. Brightness determines how many electrons are ejected.

Work Step by Step

The ejection of an electron depends on the interaction of one photon with an electron. For photons, E = hf, where E is the energy, h is Planck's constant, and f is the photon's vibrational frequency. High-frequency photons are more energetic and give an ejected electron more KE. The number of ejected electrons depends on how many photons are hitting the surface, so that depends on the brightness of the light. This is discussed on pages 585-587.
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