Waves

A progressive radio wave in a vacuum has a frequency of 75 MHz. What is the phase difference between two points on the wave that are 50 cm apart from each

other?

• 23 degrees

• 45 degrees

• 90 degrees

• 180 degrees

Which statement is correct for longitudinal waves but not correct for transverse waves?

• They can form stationary waves.

• They can only travel through a medium.

• They can transfer energy in the direction of travel.

• They consist of peaks and troughs.

A source of sound of frequency F at point Z is moving at a steady speed. The pattern of the emitted wavefronts is shown. Which statement describes the frequencies of the sound heard by stationary observers at X and Y?

• frequency heard at X: <F and frequency heard at Y: <F

• frequency heard at X: <F and frequency heard at Y: >F

• frequency heard at X: > F and frequency heard at Y: <F

• frequency heard at X: >F and frequency heard at Y: > F

A wave of frequency 15 Hz travels at 24 m/s through a medium. What is the phase difference between two points 2.0 m apart?

• There is no phase difference.

• They are out of phase by a quarter of a cycle.

• They are out of phase by half a cycle.

• They are out of phase by 0.80 of a cycle.

Which row describes a longitudinal wave and a medium through which it can travel?

• A

• B

• C

• D

An observer is situated at the top of a tall tower. An aeroplane emitting sound at a frequency of 1000 Hz approaches the observer at a speed of 165 m/s.

The speed of sound is 330 m/s. What is the frequency of the sound received by the observer?

• 330 Hz

• 667 Hz

• 1000 Hz

• 2000 Hz