Conceptual Physics (12th Edition)

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

Chapter 30 - Think and Explain - Page 579-581: 57


It takes more energy to ionize an atom (completely remove an electron from it) than to excite the electron to a higher energy state.

Work Step by Step

For photons, E = hf, where E is the energy, h is Planck's constant, and f is the photon's vibrational frequency. A higher-frequency uv photon has more energy than a visible-light photon. This is discussed on page 564. The visible-light photon isn't energetic enough to ionize the atoms, only to excite them. An ultraviolet photon has sufficient energy to eject the electron altogether.
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