Snell's Law & Refraction

Question 1

What event does Snell’s Law govern?

a. transmission
b. refraction
c. impedance

Answer 1

b. refraction

Question 2

Which of the following best describes the process described by Snell’s Law?

a. reflection with normal incidence
b. reflection with oblique incidence
c. transmission with normal incidence
d. transmission with oblique incidence

Answer 2

d. transmission with normal incidence

Question 3

True or False?

Refraction occurs at the border between two media if and only if there is oblique incidence of the wave at the boundary.

Answer 3

True

Question 4

What conditions are necessary for refraction to occur at a boundary between two media?

a. unequal acoustic impedances and normal incidence at the boundary
b. unequal densities of the media and normal incidence at the boundary
c. dissimilar propagation speeds and oblique incidence at the boundary
d. different elasticities of the media and oblique incidence

Answer 4

c. dissimilar propagation speeds and oblique incidence at the boundary

Question 5

True or False?

Refraction always occurs at the interface between two media when the propagation speeds of the media are unequal.

Answer 5

False

Question 6

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

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 6

a. it is greater than 32 degrees

Question 7

An acoustic wave in medium B is traveling toward medium A. The sound beam strikes the boundary at a 45 degree angle. The propagation speed is 1,547 m/sec for medium A and 1,745 m/sec for medium B. What is true of the angle of transmission?

a. it is greater than 45 degrees
b. it is less than 45 degrees
c. it is equal to 45 degrees
d. cannot be determined

Answer 7

b. it is less than 45 degrees

Question 8

True or False?

The period of a sound wave determines whether refraction will occur.

Answer 8

False

Question 9

A wave of acoustic energy is leaving soft tissue and transmitting into fat with an 86 degree incident angle. What is true of the angle of transmission?

a. it is equal to 86 degrees
b. it is less than 86 degrees
c. it is greater than 86 degrees
d. cannot be determined

Answer 9

b. it is less than 86 degrees

Question 10

An acoustic wave is in medium A and traveling toward medium B. The sound beam’s angle of transmission into medium B with relation to the boundary is 79 degrees. Sound’s propagation speed is 1,547 m/sec in medium A and 1,745 m/sec in medium B. If reflection and transmission both occur at the boundary, what can be said of the reflection angle?

a. it is greater than 79 degrees
b. it is less than 79 degrees
c. it is equal to 79 degrees
d. cannot be determined

Answer 10

b. it is less than 79 degrees

Question 11

Sound propagates from one medium with a density of 1.16 kg/m^3 to a second medium with a density of 1.02 kg/m^3. If the angle of transmission is 49 degrees, what can be correctly stated about the angle of incidence.

a. it is less than 49 degrees
b. it is equal to 49 degrees
c. It is greater than 49 degrees
d. it cannot be determined

Answer 11

d. it cannot be determined