Properties of Waves: Answers

Give an example of a transverse wave.

All electromagnetic waves are transverse waves. This includes radio waves, microwaves, infra-red, visible light, ultraviolet, x-rays and gamma rays. These types of waves do not need particles to carry their vibrations which means they are able to travel through a vacuum.

Give an example of a longitudinal wave.

An example of a longitudinal wave is a sound wave or an ultrasound wave. These types of waves need particles to carry their vibrations which means they cannot travel through a vacuum.

What is the main difference between a transverse and longitudinal wave?

A transverse waves transfers information and energy through vibrations which occur at right angles (perpendicular) to the direction of wave travel. A longitudinal wave travels through vibrations which occur parallel to the direction of wave travel.

How would a sound wave with high volume differ from one with a low volume?

Volume is related to the amplitude of a wave. A sound wave with a high volume will have a larger amplitude (the distance between the rest point and the peak/trough) compared to a sound wave of lower volume.

What is the speed of a wave with a wavelength of 6 meters and a frequency of 120 Hz?

The speed of a wave is calculated by multiplying its frequency by the wavelength.

120 x 6 = 720 m/s

Calculate the frequency of a wave that has a time period of 0.05 seconds.

Frequency = 1 / time period

1 / 0.05 = 20 Hz

Describe the Doppler effect.

The Doppler effect occurs when a wave is emitted from a moving source. It appears as if the frequency of the wave changes as the source moves past you (e.g. when an ambulance or police car travels past you the pitch seems to change). This happens because sound waves have a constant wave speed. As the vehicle moves, the wavefronts ahead of it bunch closer together and have a shorter frequency while the wavefronts behind become spaced out and have a longer frequency. Since frequency is related to pitch, the change in frequency results in a change in pitch.