1.1 What is Chemistry?

http://www.ck12.org Chapter 5. Electrons in Atoms

FIGURE 5.4

Wavelength of Light and Photoelectric Ef-

fect

Lesson Summary

• Light behaves both as a particle and as a wave.


• Michael Faraday discovered that light exhibited magnetic properties.


• James Maxwell demonstrated that the speed of light is constant and that light exists as a transverse wave.


• Hertz showed that light was an electromagnetic wave and only one type of electromagnetic radiation in a much
  larger electromagnetic spectrum.


• The color of light is related to its wavelength, which is the distance between two crests of a wave of light.


• The photoelectric effect occurs when sufficiently energetic electromagnetic radiation is shined on certain kinds
  of matter, causing electrons to be ejected.


• The photoelectric effect provides an example of light acting as a particle instead of a wave.

Lesson Review Questions

FIGURE 5.5

Left: Radio antenna. Right: Longwave

(CB radio) antenna

1. What type of electromagnetic radiation (what wavelength) do you suppose the antenna on each of these
   vehicles shown in theFigure5.5 is designed to receive?


2. Black lights are used for a variety of applications, including sterilization of materials. Why do you suppose
   the light is called “black light”? Are there other forms of black light?


3. The laser in an audio compact disc player uses light with a frequency of 3.844× 1014 Hz. Calculate the
   wavelength of this light in nm.