Page 399 - Schaum's Outline of Theory and Problems of Applied Physics

384 LIGHT [CHAP. 30

30.13. A medal in a plastic cube appears to be 12 mm below its upper surface. If n = 1.5 for the plastic, the depth of the
medal is actually
(a) 6 mm (c) 18 mm
(b) 8 mm (d) 24 mm

30.14. Light going from glass of n = 1.5 to ethanol has a critical angle of incidence of 63 . The index of refraction of
◦
ethanol is
(a) 0.59 (c) 1.3
(b) 0.75 (d) 2.4

Supplementary Problems

30.1. When a light beam enters one medium from another, which (if any) of the following quantities never changes—the
direction of the beam, its velocity, its frequency, its wavelength?

30.2. Is it possible for the index of refraction of a substance to be less than 1?
30.3. In Fig. 30-13, which is the refracted ray?

30.4. In Fig. 30-14, which of the diagrams could represent the path of a light ray passing through a glass plate in air?

Water Air

A

B

C
D

Fig. 30-13

Glass
plate

A B C D
Fig. 30-14