Question
Which statement about progressive waves is correct?
A They are always transverse waves.
B They can exist in solids but not liquids.
C They decrease in frequency as their speed increases.
D They transfer energy away from their source.
Answer/Explanation
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Question
Two balls float on the surface of the sea. The balls are separated by a distance of 1.30 m. A wave travels on the surface of the sea so that the balls move vertically up and down.
The distance between a crest and an adjacent trough of the wave is 0.90 m. What is the phase difference between the two balls?
A 55o B 110o C 160o D 260o
Answer/Explanation
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Question
Two identical waves are produced by sources at points P and Q. The waves travel along different
paths to reach point R, as shown.
Both waves have a wavelength of 6.0 cm. The waves are in phase at point R.
What is the phase difference between the waves as they leave points P and Q?
A 0° B 60° C 90° D 120°
Answer/Explanation
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Question
A guitar string vibrates to create a sound. The speed of the wave in the guitar string is always
440 m \(s^{–1}\). The vibrating string creates a sound wave that moves in the air with a speed of
330 m \(s^{–1}\).
Which graph shows the variation of frequency f with the wavelength \(\lambda\) for the waves in the string and in the air?
Answer/Explanation
Question
A wave of frequency 15Hz travels at 24 m s–1 through a medium.
What is the phase difference between two points 2.0 m apart?
A There is no phase difference.
B They are out of phase by a quarter of a cycle.
C They are out of phase by half a cycle.
D They are out of phase by 0.80 of a cycle.
Answer/Explanation
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