# Fourth Hour Exam

## April 25, 2000

For every question, also consider as a possible answer
E) none of the above

1. Light

A) is an electromagnetic wave!
B) is a transverse wave!
C) has a wavelength between 400 nm (for violet) and 700 nm (for red)!
D) all of the above!

2. Total internal reflection can occur when light travels

A) in air, going toward glass.
B) in air, going toward water.
C) in glass, going toward air.
D) all of the above

3. The speed of light

A) was too fast for Galileo to measure!
B) was not accurately measured or explained by Newton!
C) was very accurately measured by A A Michelson!
D) all of the above!

4. The speed of light

A) was too slow for Galileo to measure
B) was measured by Romer using astronomical data
Times for the eclipses of the moons of Jupiter.

C) was measured by Millikin using biological data
D) all of the above

5. When you view a white light source through a diffraction grating you will see brightly colored spectra with

A) red on the inside and violet on the outside
B) violet on the inside and red on the outside
C) yellow on the inside and green on the outside
D) yellow on the outside and green on the inside

6. When you see a rainbow, you see

A) red on the inside and violet on the outside
B) violet on the inside and red on the outside
C) yellow on the inside and green on the outside
D) yellow on the outside and green on the inside

7. The colored dots that make up the color on a TV screen are

A) red, yellow, green
B) red, yellow, blue
C) red, green, blue
D) cyan, magenta, yellow

8. Colors seen on TV result from color

A) subtraction
C) neither of these
D) both A) and B)

9. Colors seen in paint result from color

A) subtraction
C) neither of these
D) either of these

10. Look at a full-color picture in a magazine with a magnifying glass and you will see that the inks used are

A) red, green, cyan, and blue.
B) red, green, blue, and black.
C) Cyan, Magenta, Yellow, and blacK.
D) cyan, green, yellow, and blue.

11. A mixture of red and blue light produces

A) blue
B) magenta
C) yellow
D) cyan

12. Initially, a camera is focused at a nearby person. It is then adjusted to focus on some far-distant mountains. To do this, the lens

a) is moved closer to the film.
Ray diagrams are always very useful!

b) is moved farther from the film.
c) is "opened" to larger aperature or larger opening.
d) is "shut down" to a smaller aperature or smaller opening.

13. Different colors are dispersed by a prism because different colors in the spectrum have different

A) angular momenta
B) speeds
C) energies
D) momenta

14. The critical angle for a transparent material is the angle at and beyond which all light within the material is totally

A) absorbed
B) reflected
C) refracted
D) polarized

15. Light will not pass through a pair of Polaroid filters when their axes are

A) parallel
B) rotated 45°
C) rotated 57°
D) perpendicular

16. Light from a laser is

A) monochromatic
B) in phase
C) coherent
D) all of the above

Recall how a pin-hole camera works:

a) dilated or opened wide
c) blue
d) brown

18. Rainbows are a result of

A) dispersion and reflection.
B) dispersion and polarization.
C) reconstruction and polarization.
D) constructive and destructive interference.

19. An object is placed 60 cm from a converging lens that has a focal length of 20 cm. Make a ray diagram of this situation. From the ray diagram, characterize the image.

The image is

A) real, inverted, and larger.
B) real, inverted, and smaller.
C) virtual, upright, and smaller.
D) virtual, inverted, and smaller.

20. An object is placed 40 cm from a converging lens that has a focal length of 20 cm. Make a ray diagram of this situation. From the ray diagram, characterize the image.

The image is

A) real and inverted (and the same size)
B) virtual, inverted, and smaller.
C) virtual, upright, and smaller.
D) virtual, inverted, and larger.

21. An object is placed 30 cm from a converging lens that has a focal length of 20 cm. Make a ray diagram of this situation. From the ray diagram, characterize the image.

The image is

A) real, inverted, and larger.
B) real, inverted, and smaller.
C) real, upright, and smaller.
D) virtual, upright, and larger.

22. An object is placed 10 cm from a converging lens that has a focal length of 20 cm. Make a ray diagram of this situation. From the ray diagram, characterize the image.

The image is

A) real, inverted, and larger.
B) real, inverted, and smaller.
C) virtual, upright, and smaller.
D) virtual, upright, and larger.

23. A simple magnifier produces

A) a virtual image between the lens and your eye
B) a real image between the lens and your eye
C) a virtual image beyond the near point of your eye
D) a real image at infinity

24. A microscope uses the front lens or objective lens to produce a

A) virtual image which is right side up.
B) virtual image at infinity.
C) real image which is then viewed through the eyepiece.
D) real image which is right side up.

25. A telescope uses the front lens or objective lens to produce a

A) virtual image which is right side up.
B) virtual image at infinity.
C) real image which is then viewed through the eyepiece.
D) real image which is right side up.

26. In the interference pattern produced by shining a laser through two slits (Young's double slit experiment), the bright areas are the result of

A) destructive interference.
B) polarization.
C) constructive interference.
D) restructive construction.

27. A sheet of red paper will look black when illuminated with

A) red light
B) cyan light
C) yellow light
D) magenta light

28. The “near point” of a person’s eye is

A) always 25 cm
B) the farthest distance at which that person can clearly see an object
C) the nearest distance at which that person can clearly see an object
D) infinitly far away

29. The type of lenses needed to correct nearsighted vision is

A) converging
B) diverging
C) convex
D) concave

30. The type of lenses needed to correct farsighted vision is

A) converging
B) diverging
C) convex
D) concave

31. In an optical system with two lenses,

A) the size of the final image is the magnification of the first lens multiplied by the object
distance of the second lens.

B) the magnification of the whole system is the sum of the magnifications of the two lenses.
C) the image produced by the first lens is always virtual.
D) the image produced by the first lens can be treated as an object for the second lens.

E) None of the above.

32. A double rainbow requires

A) only one reflection inside the raindrops.
B) two reflections inside the raindrops.
C) constructive interference inside the raindrops.
D) destructive interference inside the raindrops.

It may help to make ray diagrams for the next four questions. Use the back of the exam or the back of the cover sheet to make these ray diagrams.

33. If you hold a converging lens at arm’s length and look at a classmate located at the other side of the lecture hall, you will see an image. That image is

A) real, inverted, smaller.
B) virtual, upright, smaller.
C) virtual, inverted, larger.
D) real, upright, larger.

34. If you hold a converging lens close to your thumb you will see an image. That image is

A) real, inverted, smaller.
B) virtual, upright, larger.
C) virtual, inverted, smaller.
D) real, inverted, larger.

35. If you hold a diverging lens at arm’s length and look at a classmate located at the other side of the lecture hall, you will see an image. That image is

A) real, inverted, smaller.
B) virtual, upright, smaller.
C) virtual, inverted, larger.
D) real, upright, larger.

36. If you hold a diverging lens close to your thumb you will see an image. That image is

A) real, inverted, smaller.
B) real, inverted, larger.
C) virtual, inverted, smaller.
D) virtual, upright, larger.

E) None of the above; the image is virtual, upright, and smaller.

37. Many or most binoculars “fold” the path of the light, to make the binoculars more compact, by using reflections inside of prisms. Thes reflections are the result of

A) population inversion and optical pumping.
B) partially silvered mirrors.
C) frustrated external reflection.
D) total internal reflection.

38. When you look at a fish in an aquarium, the fish is really

A) closer than its image that you see.
B) located just where you see the image.
C) farther away than its image that you see.

39. Albert Einstein received the Nobel Prize in Physics for

A) Special Relativity.
B) General Relativity.
C) the Photoelectric Effect.
D) his Theory of Image Formation.

Einstein's Theory of Relativity was still very controversial. His explanation of the Photoelectric Effect was not controversial.

40. Young’s double slit experiment, in 1801, clearly showed that light is composed of

A) particles.
B) waves.
C) mutually interacting particles.
D) exclusively non-interactive particles.

41. Early, accurate, and important measurements of the speed of light were made in the US by

A) Tycho Brahe.
B) A A Michelson. (USNA; Case Institute of Technology; Western Reserve University).
C) Milliken.
D) Isaac Newton.

42. Light can be bent by

A) reflection, refraction, subtraction, and resonance.
B) regression, progression, diffraction, and scattering. (From "Intro to Optics" video).
C) reflection, refraction, sublimation, and amortization.
D) reflection, refraction, diffraction, and scattering.

43. Explaining the Photoelectric Effect requires that light be composed of

A) longitudinal EM waves.
B) waves.
C) particles.
D) all of the above.

Is light a wave or a stream of particles? Is an electron a particle or a wave? These questions occupied the best and brightest young talents for the first quarter of the previous century.

44. We see interference effects if a laser is shined at or through a double slit (this is Young’s double slit experiment). We do not see interference effects due to the light coming from two flashlights because their light is

A) coherent.
B) incoherent.
C) too dim.
D) too bright.

45. When light passes through a narrow slit, the light

A) becomes longitudinal.
B) is polarized perpendicular to the slit.
C) is polarized parallel to the slit.

46. Consider light passing through a single slit. As the slit is made more narrow, the light

A) becomes more longitudinal.
B) becomes is more greatly polarized.
C) is reduced in frequency.

47. Consider a scuba diver under a very still, calm, flat, plane water’s surface. As the scuba diver looks up, what will be seen?

A) Objects above the water will be seen but distorted so they appear lowerer than they really are. Objects below the water may also be seen by partial external reflection.
B) Objects above the water will be seen but distorted so they appear higher than they really are. Objects below the water may also be seen by total internal reflection.
C) Objects above the water will not be seen. Only objects below the water will be seen.
D) Objects above the water will not be seen. Objects below the water may also be seen by total internal reflection.

48. Again, consider a scuba diver under a very still, calm, flat, plane water’s surface. As the scuba diver looks up, what will be seen?

A) Objects actually located above the surface may be seen below the surface due to total internal reflection.
B) Objects actually located above the surface may be seen below the surface due to partial polarization.
C) Objects actually located below the surface may be seen above the surface due to total internal reflection.
D) Objects actually located below the surface may be seen above the surface due to polarization at the interface.

49. The "depth of field" increases as a camera’s lens is

A) “stopped down” or closed to allow in less light.
The system acts more like a pin-hole camera.

B) opened up so more light can come in.
C) given a greater effective focal length (as with a zoom lens)

50. The "Complimentarity Principle" or the "Wave-Particle Duality of Nature" was proposed by

A) Sir Isaac Newton in England.

B) Niels Bohr in Denmark.

C) A A Michelson in the US.

D) Hienrich Hertz in Germany

Is light a wave or a stream of particles? Is an electron a particle or a wave? These questions occupied the best and brightest young talents for the first quarter of the previous century. It was Niels Bohr, at the University of Copenhagen, who proposed the "Complimentarity Principle" saying that both the wave model and the particle model are needed to compliment each other. They compliment rather than contradict each other.