Page 398 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 30] LIGHT 383

30.2. Electromagnetic waves transport
(a) frequency (c) charge
(b) wavelength (d) energy

30.3. A transparent medium has an index of refraction that is
(a) less than 1 (c) greater than 1
(b) 1 (d) any of the above

30.4. For total internal reflection to occur when light passes from one medium to another, the second medium must have
an index of refraction relative to that of the first medium that is
(a) lower (c) higher
(b) the same (d) any of the above, depending on the angle of incidence

30.5. The unit of the luminous intensity (brightness) of a light source is the
(a) lumen (c) footcandle
(b) lux (d) candela

30.6. The minimum illumination recommended for reading is
(a) 800 cd (c) 800 lx
(b) 800 lu (d) 800 W

30.7. A hemisphere subtends a solid angle about its center of
(a) π/2sr (c) 2π sr
(b) π sr (d) 4π sr

2
30.8. The luminous flux emitted by an isotropic light source is concentrated on an area of 0.5 m whose illumination is
750 lx. The luminous intensity of the light source is
(a) 30 cd (c) 375 cd
(b) 60 cd (d) 4712 cd

8
30.9. The velocity of light in diamond is 1.24 × 10 m/s. The index of refraction of diamond is
(a) 1.24 (c) 2.42
(b) 2.31 (d) 3.72

◦
30.10. Light goes from medium A to medium B at an angle of incidence of 40 . The angle of refraction is 30 . The velocity
◦
of light in medium B is
(a) less than in A (c) greater than in A
(b) the same as in A (d) any of the above, depending on the specific media involved

◦
30.11. Light enters a glass plate at an angle of incidence of 25 . If the index of refraction of the glass is 1.6, the angle of
refraction is
(a) 15 ◦ (c) 40 ◦
(b) 16 ◦ (d) 43 ◦

◦
30.12. A diver with a flashlight shines a light beam upward from the bottom of a pool at an angle of incidence of 40 . The
light leaves the surface of the pool at an angle of refraction of 60 . The index of refraction of water is
◦
(a) 0.67 (c) 1.3
(b) 0.74 (d) 1.5