PHY 101.002†† Test 2†††† †††††††††††† ††††††††Answers†††† †††††††††††††††††††††† ††††October 18, 2007

 

Read each question and its set of answers very carefully.There is only one best answer for each question.Donít be afraid to ask questions of me during the exam.Just raise your hand if you have one.

 


 

1.Which color is associated with the highest frequency of visible electromagnetic waves?

(a) blue†††††††††††

(b) red†††††††††††††††††††††

(c) green

(d) violet††††††††††††††††††

(e) magenta

 

2.The speed of light

(a) has never been measured

(b) is about the same as that of sound

(c) is infinitely fast

(d) is very fast, but not infinite

 

3.Consider light energy that is momentarily absorbed in glass and then re-emitted.Compared to the absorbed light, the frequency of the re-emitted light is

(a) considerably less††††††††††

(b) slightly less

(c) the same†††††††††††††††††††††††

(d) slightly more

(e) considerably more

 

4.You are standing on the earth viewing a total eclipse of the sun.In which shadow of the moon are you standing?

(a) the penumbra††††††††††††††††

(b) the umbra

(c) the conundrum†††††††††††††

(d) the partial

 

5.If he (she) says "I love you" and the pupils of his (her) eyes are large, then most likely he (she) means it.

(a) True††††††††††

(b) False

 

6.Mark the incorrect statement.

(a) the cones in the human eye can sense color

(b) the rods in the human eye provide our black and white vision

(c) the rods in the human eye detect low intensity light better than the cones

(d) the diameter of the pupil in the human eye never changes for a person of normal vision

 

7.Why can't we see stars in the middle of the day?

(a) the sun is much brighter than any star

(b) our atmosphere is more turbulent and the starlight is refracted away

(c) scattered sunlight hides the stars from our view

(d) our atmosphere totally absorbs the starlight

 

8.When light is behaves like a particle, we call it

(a) a proton ††††††††††††††††††††††

(b) a phonon

(c) a photon ††††††††††††††††††††††

(d) an electron

(e) a wavicle

 

9.A beam of red light and a beam of blue light have exactly the same energy.Which beam has the greater number of photons?

(a) red

(b) blue

(c) they both have the same number of photons

 

10. The energy levels of an atom are continuous because an electron can occupy any of an infinite number of orbits about the nucleus of an atom.

(a) True ††††††††††††††††††††††††††††

(b) False

 

11. What type of spectrum would you expect to obtain if sodium is burned and analyzed by a spectroscope?

(a) an emission spectra of sodium

(b) an absorption spectra of sodium

(c) a continuous spectrum

 

12. Which is hottest?

(a) a red hot object ††††††††††††

(b) a blue hot object

(c) a white hot object

 

13. What type of spectrum would you expect to obtain if white light is shined through sodium vapor?

(a) an emission spectrum of sodium

(b) an absorption spectrum of sodium

(c) a continuous spectrum

 

14. Atoms of a phosphorescent material on the average stay excited longer than atoms of a fluorescent material.

(a) True ††††††††††††††††††††††††††††

(b) False

 

15. The light from a laser is coherent.This means that all of the light has

(a) the same phase ††††††††††††

(b) the same frequency

(c) the same direction †††††††††††††††††

(d) all of the above

(e) none of the above

 

16. The color of an opaque object is the same as the light that

(a) is transmitted†††††††

(b) is absorbed†††††††††

(c) is reflected

(d) all of these

(e) none of these

 

17. A green shirt is green because

(a) electrons spontaneously de-excite and radiate light in the frequency range of green

(b) all except green frequencies are reflected when white light shines on the shirt

(c) green light is reflected when white light shines on the shirt

(d) the dyes in the shirt have phosphors

 

18. A red filter will warm more from ††††††††††† light.

(a) red††††††††††††††††††††††

(b) cyan

 

19. Magenta light is really a mixture of

(a) red and blue light †††††††††

(b) red and cyan light

(c) red and yellow light ††††††

(d) yellow and green light

 

20. What is the resulting color of equal intensities of blue light and green light combined?

(a) cyan††††††††††

(b) yellow††††††††††††††††

(c) red

(d) magenta††††††††††††††

(e) white

 

21. If sunlight were green instead of white, the most comfortable color to wear on a hot day would be

(a) magenta †††††††††††††††††††††††

(b) yellow

(c) green †††††††††††††††††††††††††††

(d) blue

(e) none of these

 

22. Mixing yellow paint and magenta paint gives what color?

(a) red †††††††††††††††††††††

(b) green

(c) blue †††††††††††††††††††

(d) cyan

 

23. Which color is not in the spectrum of white light?

(a) magenta †††††††††††††††††††††††

(b) blue

(c) green †††††††††††††††††††††††††††

(d) yellow

(e) orange

 

24. What color would you expect to see if you remove the green light from white light?

(a) yellow††††††††††††††††††††††††††

(b) cyan

(c) magenta

 

25. The sun appears slightly yellowish when viewed from the earthís surface because

(a) that is its natural color

(b) its surface emits more yellow light than any other color

(c) the sunlight cools off as it passes through the earthís atmosphere

(d) the earthís atmosphere scatters more blue light than it does red light

 

26. The after image of an object shows the complementary colors of the object.

(a) True ††††††††††††††††††††††††††††

(b) False

 

27. Light will almost always travel from one place to another along a path of least

(a) distance††††††††††††††††††††††††

(b) time

(c) effort††††††††††††††††††††††††††††

(d) expense

(e) complication

 

28. Which type of specular reflector can focus light?

(a) convex shoplifting mirror††††††††

(b) flat mirror

(c) concave make-up mirror

(d) diffuse mirror

 

29. What is the difference between a real image and a virtual image?

(a) a real image is always erect; a virtual image can be inverted

(b) a real image is always bigger than the object; a virtual image can be smaller

(c) a real image can be formed on a screen; a virtual one cannot

(d) there is no difference; what you get depends only on the type of mirror

 

30. The law of reflection requires that the sum of the angle of incidence and the angle of reflection equals 90o.

(a) True ††††††††††††††††††††††††††††

(b) False

 

31. The screen in a microwave oven door that allows one to see the food inside the oven is a specular reflector for

(a) visible light††††††††††

(b) infrared heat

(c) microwaves††††††††††††††††††

(d) ultraviolet light

 

32. If rays of light parallel to the optic axis (principal axis) are incident on a                mirror, they converge to a point after leaving the mirror.

(a) flat††††††††††††††††††††††

(b) convex

(c) concave†††††††††††††††††††††††

(d) diffuse

 

33. The image in a plane mirror is real because you can see it with the naked eye.

(a) True ††††††††††††††††††††††††††††

(b) False

 

34. A wire mesh screen is a diffuse reflector for which of the following frequencies?

(a) visible ††††††††††††††††††††††††††

(b) microwave

(c) radio

 

35. An oar partially immersed in water appears "broken" because of

(a) refraction ††

(b) diffraction

(c) polarization ††††††††

(d) interference

(e) absorption

 

36. Refraction results from differences in lightís

(a) frequency†††††††††††††††††††††

(b) incident angles

(c) speed†††††††††††††††††††††††††††

(d) all of these

(e) none of these

 

37. In mirages the air next to the ground must be †††††††††††than the air above it.

(a) more reflective †††††††††††††

(b) warmer

(c) cooler †††††††††††††††††††††††††

(d) thicker

 

38. Which of the following is due to refraction of light?

(a) squatty body images of people standing in water

(b) mirages

(c) looming

(d) all of the above

(e) none of the above

 

39. For the drawing below which ray is most likely red?

(a) 1 ††††††††††††††

(b) 2†††††††††††††††

(c) 3

 

 

 

 

 

 


 

40. Two people standing next to each other are looking at the same raindrop in a regular rainbow.One sees green from that drop and the other sees orange.Which person is taller?

(a) the one who sees green

(b) the one who sees orange

(c) both are the same height

(d) height has nothing to do with this phenomenon