Reflection & Transmission

Question 1

If the ___ of two media are different and sound strikes a border between the media at 90degrees incidence, then reflection will occur.

a. conductances
b. densities
c. impedances
d. propagation speeds

Answer 1

c. impedances

Question 2

True or False?

The proportion of the incident intensity that is reflected at a border between two media will increase as the impedances of the media become increasingly dissimilar.

Answer 2

True

Question 3

A sound pulse strikes a boundary between two media with normal incidence. The speed of sound in the two media are very different; however, the impedances of the media are identical. What will happen?

a. a big echo will be produced
b. a medium echo will result
c. a small echo will result
d. there will be no echo at all

Answer 3

d. there will be no echo at all

Question 4

Two acoustic waves strike a boundary between two media. The waves are traveling in a direction 90 degrees to the boundary. Reflection of these waves depends on differences in the ____.

a. frequencies of the two waves
b. propagation speeds of the two media
c. amplitudes of the two waves
d. impedances of the two media

Answer 4

d. impedances of the two media

Question 5

An ultrasound wave approaches an interface between two media at a 90 degree angle. The propagation speeds and the densities of the two media are different. Which is correct?

a. reflection will definitely occur
b. reflection will definitely not occur
c. refraction may occur
d. none of the above

Answer 5

d. none of the above

Question 6

An ultrasound wave strikes an interface between two media at a 90 degree angle. The propagation speeds of the media are identical. However, the densities of the media are different. Which is true?

a. reflection will definitely occur
b. reflection will definitely not occur
c. refraction may occur
d. none of the above

Answer 6

a. reflection will definitely occur

Question 7

An acoustic wave is traveling from medium X to medium Z. Medium X has a propagation speed of 1,457 m/sec and an impedance of 1.44 MRayls. Medium Z’s propagation speed is 1,644 m/sec and its impedance is 1.26 MRayls. The angle of incidence is 32 degrees. What is true of the angle of reflection?

a. it is greater than 32 degrees
b. it is equal to 32 degrees
c. it is less than 32
degrees
d. cannot be determined

Answer 7

b. it is equal to 32 degrees

Question 8

True or False?

When reflection occurs with oblique incidence, the angle of reflection equals the angle of incidence. This is known as Snell’s Law.

Answer 8

False