24 April 2011

Use the diagram to answer the questions

Two speakers are arranged so that sound waves with the same frequency are produced and radiate through the room. An interference pattern is created (as represented in the diagram at the right). The thick lines in the diagram represent wave crests and the thin lines represent wave troughs.

1. At which of the labeled point(s) would constructive interference occur?

a. B only

b. A, B, and C

c. D, E, and F

d. A and B

Answer: D 

Both points A and B are on locations where a crest meets a crest.

2. How many of the six labeled points represent anti-nodes?

a. 1 b. 2 c. 3 d. 4 e. 6

Answer: B 

Only points A and B are antinodes; the other points are points where crests and troughs meet.