Physics 72: Chapter 33 Problem Set Summer 2010

Name: Score: Lecturer: Mr Carlos Baldo III Section: X7-7

Encircle the letter of the correct answer. Solve each problem clearly and completely for full credit. 1. Refraction. Light passes from a material with index of refraction 1.2 into one with index of refraction 1.4.

Compared to the incident ray, the refracted ray ___________. A. is undeflected. B. travels at a faster speed. C. bends toward the normal. D. bends away from the normal. E. bends parallel to the surface.

2. Ray of Light. A light ray of wavelength 555 nm traveling through air is incident on a smooth, flat slab of

glass (n = 3 ) at an angle of 60.0° with respect to the normal. What is the angle of refraction?

A. 0.0° B. 30.0° C. 45.0°

D. 60.0° E. 90.0o

3. Neyo versus Nemo. Hiding behind the bushes, Neyo directly shoots Nemo, who is swimming underwater,

using his ultra-deadly laser gun. Compared to the transmitted beam, the incident laser beam _______. A. travels at a faster speed B. is more bent towards the normal to the air-water interface C. travels at a slower speed D. B and C E. A and B

4. Sosyal death. Feeling safe, Ingrid swims underwater to get away from her notorious killers. Unfortunately, her blue diamond chest pendant glows brightly and this is seen by one of the killers. If he is to shoot Ingrid at the chest using his M16, where should he aim Ingrid?

A. directly downward B. directly upward C. directly where he sees the glowing pendant D. below the position where he sees the glowing pendant E. above the position where he sees the glowing pendant

5. Amazing. A glass rod with n=1.76 is immersed partly in straight position, into an oily compound with n=1.76. The part of the glass rod immersed in the compound _________.

A. appears black B. appears invisible C. appears more bent from the normal to the interface D. appears less bent from the normal to the interface E. appears parallel to the normal to the interface

6. Pity Nemo. Nemo, trying to escape inside a glass fiber, transforms into a laser beam. He strikes the glass-air interface at angle of incidence equal to 300. Unfortunately, he bounces back into the glass material. What could be its refractive index?

A. 2 B. 1 C. 1/2

D. 2/√3 E. √3/2

7. TIR in a dragonball. The critical angle for total internal reflection in a piece of dragonball crystal

surrounded by air is about 30°. What is the index of refraction of this material?

A. 1

B. 2

C. 2

D.

2

2

E.

2 3

3

Physics 72: Chapter 33 Problem Set Summer 2010

8. Reflections. Mulan, reflecting on her past experiences, looks at her reflection on a calm pond surface. What could be the sufficient condition so that the reflected light becomes linearly polarized? Note: nwater = 1.34

A. θ=tan (1.34) B. θ=tan-1 (1/1.34) C. θ=tan-1 (1.34) D. θ=sin-1 (1/1.34) E. θ=sin-1 (1.34)

For the next two questions, consider three translucent liquid soap brands X, Y and Z that are tested via optical

beam transmission. The resulting test generates ray tracing illustration such as shown in the figure. 9. Who’s better? Compare the refractive indices of the three soap brands.

A. nx = ny = nz B. nx < ny < nz C. nx > ny > nz D. nx = ny > nz E. nx > ny = nz

10. Speed babad. Compare the relative speeds of light inside each soap. A. vx = vy = vz B. vx < vy < vz C. vx > vy > vz D. vx = vy > vz E. vx > vy = vz

11. Dispersion. The dispersion curve is given in the figure. Which of the following statements is TRUE about the speed of various colors of light in a glass?

A. All colours of light have the same speed in glass B. Red has the highest speed, violet the lowest C. Violet has the highest speed, red the lowest D. Green has the highest speed, red and violet the lowest E. Red and violet have the highest speed, green the lowest

12. Blue. Bluish lights (λvacuum=510nm) is incident onto a transparent material with refractive index n=2. What will be its wavelength and frequency inside the material?

A. 255nm, (3/510) x 1017 Hz B. 255nm, (3/255) x 1017 Hz C. 510 nm, (3/1020) x 1017 Hz D. 510nm, (3/510) x 1017 Hz E. 510nm, (3/255) x 1017 Hz

For the next two numbers, consider a slimy sticky green paste with electrical permittivity 8εo and magnetic permeability 2µo.

13. Slimy sticky green paste 1. Compute for the index of refraction of this material.

A. ½ B. 1 C. 2 D. 4 E. 8

14. Slimy sticky green paste 2. If light with electric field amplitude Eo is incident to the material, what is its intensity inside the slimy paste? Note: c = speed of light in vacuum

A.

21

2o ocEε

B. 2

o ocEε

C. 2

2o ocEε

D. 2

4o ocEε

E. 2

8o ocEε

Physics 72: Chapter 33 Problem Set Summer 2010

15. Secret code. A secret code given as 6 letters projected by 6 different linearly polarized light sources. The angle of polarization (measured with respect to the vertical) of each letter is given. If you look at the code through a polarizer whose transmission axis is along the vertical, what word will you see?

A. RA – ancient Egyptian sun god B. BAT – the secret headquarter of a fictional superhero C. BATH – pertaining to Mr. James Bath, former director

Bank of Credit D. BRAH – shortcut name for the god of creation in Hinduism E. BETH- the old lady who owns 40 dressed Chihuahuas

16. So intense. An unpolarized beam of light is incident onto a polarizer. At any orientation of the polarizer axis, the light transmitted is 10 W/m2. What is the intensity of the incident beam?

A. 5 W/m2 B. 10 W/m2 C. 20 W/m2 D. 40 W/m2 E. 50 W/m2

17. Polarizers. Three polarizing filters are stacked, with the polarizing axes of the second and third at angles θθθθ

and 90°, respectively, with that of the first. Unpolarized light of intensity Io is incident on the stack. For what value of θθθθ does the maximum transmission occur?

A. 0° B. 30° C. 45° D. 60° E. 90o

18. Brewster’s Law. Light from air is incident on a flat greenish sticky gum at polarizing angle equal to 60°. What is the index of refraction of this substance?

A. 1

B. 2

C. 3

D.

3

3

E.

2 3

3 19. Fuchsia. Blue and fuchsia lights are both incident to a mirror at the same angle of incidence. However, only

blue light is reflected back. Which of the following statements could be TRUE? A. The incident fuchsia light is linearly polarized while incident blue light is unpolarized. B. The incident fuchsia light is unpolarized while incident blue light is linearly polarized C. Both incident fuchsia and blue lights are linearly polarized. D. Both incident fuchsia and blue lights are unpolarized.

20. Color Absorption. A gas absorbs red and violet and scatters orange light. Its color is most likely _______. A. red B. violet C. blue D. orange E. fuchsia

21. Mundong Makulay. Which of the following is/are accounted for the formation of rainbows?

I. Reflection and Refraction II. Dispersion

III. Scattering IV. Polarization

A. I only B. II only C. I and II D. I, II and III E. I, II, III and IV

Physics 72: Chapter 33 Problem Set Summer 2010

22. Reflection. The fraction of incident light that gets reflected is ____________ at normal incidence and ____________ at grazing incidence, θi = 90°.

A. maximum; maximum B. minimum; maximum C. maximum; minimum D. minimum; minimum

23. Slab. A ray of monochromatic (single-color) light in air falls on the upper surface of two transparent parallel-sided slabs of different indices of refraction. The index of refraction of the lower slab is approximately __________.

A. √6 B. √3 C. √2 D. (√3)/2 E. ½

24. Brewster’s angle. Unpolarized light traveling in air strikes a glass plate at Brewster’s angle with respect to the normal. Part of the beam is reflected and part is refracted. The reflected and refracted beams make an angle of 90° with each other. Which of the following statement/s is/are TRUE?

A. The reflected beam is 100% polarized. B. The refracted beam is 100% polarized. C. The refracted beam is partially polarized. D. A and B E. A and C

25. Apparent angle. An underwater scuba diver sees the Sun at an angle of 45.0° from the normal to the interface. What is the actual elevation angle of the Sun with respect to the normal of the air-water interface?

A. Greater than 45.0° B. Less than 45.0° C. Equal to 45.0° D. Overhead (0o) E. Cannot be determined

26. The Normal incident. Light is incident normally on the short face of a 30°-60°-90° prism. A drop of liquid

is placed on the hypotenuse of the prism. If the index of the prism is 3 , what is the maximum index that the liquid should have if the light is to be totally reflected?

A. 1 B. √2 C. 3/2 D. √3 E. 2

27. Gummy-Nemo. Consider a gummy bear on a boat peeking at Nemo underwater as shown. How does Nemo appear as seen by the gummy bear? Note: nwater = 4/3.

A. Nemo appears far from the air-water interface. B. Nemo appears close to the air-water interface. C. Nemo is larger than his original size. D. Nemo is smaller than his original size. E. A and D

28. Wavelength-speed. What is the wavelength of a monochromatic light in vacuum if its speed and wavelength in a heavy flint glass is 1.50 x 108m/s and 540 nm, respectively?

A. 135 nm B. 270 nm C. 540 nm D. 675 nm

E. 1080 nm The SAND Prince