Chapter 21 Problem
1.
Visible light having a wavelength of 6.010-7 m appears orange. Compute (a) the frequency
and (b) energy of a photon of this light. Round up to 3 significant digits. (c: 3108 m/s, h:
6.6310-34 Js)
2.
Compute the velocity of light in diamond, which has a dielectric constant r of 5.3 (at
frequencies within the visible range) and a magnetic susceptibility (m) of -2.1110-5. Use
scientific notation. (0: 8.8510-12 F/m, 0: 410-7 H/m)
3.
Select what determines the characteristic color of a metal.
□ The characteristic color is determined by the distribution of wavelengths of the
nonabsorbed light radiation that is reflected.
□ The characteristic color is determined by the distribution of wavelengths of the
nonabsorbed light radiation that is transmitted through the material.
4.
(a) At the end of Section 21.14 it was noted that the intensity of light absorbed while passing
through a 20-kilometer length of optical fiber glass is equivalent to the light intensity absorbed
through for a 25-mm thickness of ordinary window glass. Calculate the absorption coefficient
 of the optical fiber glass if the value of  for the window glass is 510-4 mm-1. What is the
fraction of light transmitted through the window glass, I T' / I 0' ?
(b) What is the absorption coefficient, , for the optical fiber glass? Use scientific notation.
5.
Select the description of the opaque materials.
□ Light is transmitted diffusely through the materials (there is some internal light scattering).
Objects are not clearly distinguishable when viewed through them.
□ Virtually all of the incident light is transmitted through the materials, and one can see
clearly through them.
□ The materials are impervious to light transmission; it is not possible to see through them.
6.
The index of refraction of polyethylene within the visible spectrum is 1.51. Determine the
fraction of the relative dielectric constant at 60 Hz that is due to polarization, using data shown
in the table below. Neglect any orientation polarization effects.
7.
The index of refraction of quartz is anisotropic. Suppose that visible light is passing from one
grain to another of different crystallographic orientation and at normal incidence to the grain
boundary. Calculate the reflectivity at the boundary if the indices or refraction for the two
grains are 1.550 and 1.560 in the direction of light propagation.
8.
A semiconducting material has a band gap of 2.24 eV. What are the (a) minimum, and (b)
maximum wavelengths of visible light at which the material is transparent. (c: 3108 m/s, h:
4.1310-15 eVs)
9.
The fraction of nonreflected radiation that is transmitted through a 10-mm thickness of a
transparent material is 0.90. If the thickness is increased to 20 mm, what fraction of light will
be transmitted?
10. Compute the difference in energy between metastable and ground electron states for some laser
material that emits monochromatic light having a wavelength of 0.6943 m. Values for
Planck’s constant and the velocity of light in a vacuum are 4.1310-15 eVs, and 3108 m/s,
respectively.