Sample Tests

1. A wave is traveling from left to right across the page. For each type of wave listed, choose the figure which represents the full motion of what is waving.

 a) Sound Waves in Air b) Light Waves c) Water Waves d) String Waves
 2. The two waves are traveling in opposite directions as indicated by the arrows. When they have each moved two blocks horizontally, they are overlapping.

3. A source of sound waves is creating waves of frequency f (cycles/sec). If the source moves away from you, "pulling the crests farther apart", what will happen to the frequency of the waves you hear? To the velocity of the waves? Explain WHY you chose the answers below.

f increases f decreases f unchanged

v increases v decreases v unchanged

 4. Locate the images of the number 4 in the double mirrors placed at 90° as shown. Put in images in proper position(s) and orientation. Draw rays to the eye to show the path taken by light when "seeing" each image. Use different colors for "seeing" each image.
 5. Crests of waves from sources at A and B are shown in the diagram. Using "x"s for points of contructive interference and "o"s for points of destructive inter-ference, locate at least three "lines" along which waves travel constructively and show the points of "brightness" along line C D. Briefly describe below how a hologram is made.... include a labeled picture.

 6. In the representa-tion of a wave in the drawing, vertical height is measured in cm. Horizontal axis could be time in seconds or distance in meters.

a) What is the amplitude of the wave?

b) If horizontal axis is measured as time, what is the frequency of the wave?

c) If the horizontal axis is measured as distance, what is the wavelength of the wave?

d) Using the results of parts b) and c), what would be the velocity of the wave?

e) If this wave represents a sound wave in air and the wave is moving along the line below, and the dot represents a particle of dust in the air, show the motion of the particle due to the wave.

 7. Shown at right is a wave on a string of length L.

a) What is the "name" of such a wave? That is, what do we call such a wave? And what do we call Point A? What do we call point B?

b) Describe the "physics" of producing such a wave... how can a spot on the string not move?

c) If the length of the string is 80 cm, what is the "wavelength" of the wave?

d) If the frequency of the oscillator is 120 Hz, what is the velocity of the waves on the string?

e) Without changing the length of the string or the frequency of the oscillator, what could you do to produce 5 patterns, instead of 4, on the string?

 8. The rectangular-shaped wave (A) is moving to the right and the triangular-shaped wave (B) is moving to the left. At the instant shown they are moving through the same region of the string. On the line below the waves, draw the wave as it would appear on the string. (At each point along the string, their amplitudes add.)

 9. Complete the drawing of the making of a hologram of object F as shown at right. Give an appropriate "name" for each of the items listed A - G.

Which of the lettered items would you remove to view the hologram, leaving the others in place?

10. a) Two different continuous waves produced on the surface of a pond would be expected to have the same: (Choose all the correct answers)

1. frequency

2. energy

3. wave speed

4. amplitude

5. wavelength

b) How could you produce a continuous wave on the surface?

c) Give a relationship which must exist between some of the quantities listed in part a).

11. The two waves shown in the drawing below are passing each other in opposite directions on a string. Sketch the shape of the resultant wave at the instant shown. State the basic "rule" for interference which led you to your final sketch.

12. a) Where do X-rays come from?

b) The velocity of electromagnetic waves is 3 x 108 m/s. Infrared waves have a wavelength of approximately 10-15 m. What is the frequency of such an infrared ray?

c) Draw a sketch of a ray coming from the sun, through the raindrop, into your eye which would be part of a rainbow. The sun is not shown. What laws must the light obey to accomplish this amazing feat?

 13. A tube of air of length 0.66 m is open at both ends. The speed of sound is 330 m/s. a) Each end of the pipe would have a _________. b) If this is a fundamental wave in the tube, the center of the pipe would have a _________.

c) Draw the fundamental pattern in the tube.

d) What would be the frequency of the sound in the pipe?

e) If you covered one end of the tube would the fundamental frequency be higher or lower than calculated in d)? Explain how you got your answer.

14. A string 120 cm long is put into vibration by a variable frequency source set at 80 Hz and produces the pattern shown below.

a. What is the wavelength of the wave shown?

i. What is the speed with which waves are traveling along the string?

ii. You wish to have only four loops on the string; list three ways in which you could accomplish. Indicate in each case whether you would increase or decrease the quantity.

15. The two eyes are looking down into a pool of water with a penny at the bottom. Draw rays from the penny which will enter each eye and determine where the eyes will "see" the penny. What law did you use?

16

Which wave travels faster, radio waves or light waves?

Which has higher frequency?

Which wave has longer wavelength?

What does a Polaroid do to light passing through it?

a. Light waves are transverse waves.

b. Light waves will not travel through a vacuum.

c. Light waves carry electrons with them.

d. Light waves are caused by electrons jumping orbits in atoms.

 18. The eye can see the real smiley face at A but also sees another face upside down in the air which isn't really there. Show the rays coming from real face that allows eye to see each. What property of waves is used to see the face out of water?