6.6.1 Waves in air, fluids and solids

Question 1

What are the two families of wave?

Answer 1

Transverse and longitudinal

Question 2

What are examples of a transverse wave?

Answer 2

Electromagnetic waves
Water waves
Secondary seismic waves

Question 3

What are examples of a longitudinal wave?

Answer 3

Sound waves

Primary seismic waves

Question 4

What are the top and bottom of a transverse wave called?

Answer 4

top - peak/crest

bottom - trough

Question 5

What are the different regions in a longitudinal wave called?

Answer 5

particles close together - compression

particles far apart - rarefaction

Question 6

What is the definition of a wave?

Answer 6

Something which transfers energy (or information) from one place to another without transferring matter (material).

Question 7

How do the particles move in a transverse wave?

Answer 7

The particles oscillate perpendicular (at 90 degrees) to the direction of wave travel.

Question 8

How do the particles move in a longitudinal wave?

Answer 8

The particles oscillate parallel (at 90 degrees) to the direction of wave travel.

Question 9

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

Answer 9

In a transverse wave the particles oscillate perpendicular (at 90 degrees) to the direction of wave travel.
In a longitudinal wave the particles oscillate parallel (at 90 degrees) to the direction of wave travel.

Question 10

Give a piece of evidence that no matter moves when a wave travels.

Answer 10

A ball on water moves up and down as the wave moves from left to right.
Sand particles in a resonance tube vibrate in fixed positions as a wave moves down the tube.

Question 11

What is the definition of the amplitude of a wave?

Answer 11

The maximum displacement moved by a particle on a wave from its rest/mean/equilibrium/undisturbed position.
The distance from the equilibrium position to the top of a peak or bottom of a trough on a transverse wave.

Question 12

What is the definition of the wavelength of a wave?

Answer 12

The distance between two identical points on a wave e.g. two adjacent peaks or two troughs

Question 13

What is the definition of the frequency of a wave?

Answer 13

The number of complete oscillations (waves) passing a point per second.

Question 14

What is the definition of the time period of a wave?

Answer 14

The time taken for one complete oscillation.

Question 15

What is the unit of frequency?

Answer 15

Hertz (Hz)

Question 16

What is the definition of wave speed?

Answer 16

The speed at which energy is transferred (or a wave moves) through a medium.

Question 17

What is the wave equation?

Answer 17

wave speed (m/s) = frequency (Hz) x wavelength (m)

Question 18

What is the symbol for wavelength?

Answer 18

λ

Question 19

Describe a method to measure the speed of sound in air outside.

Answer 19

Measure a distance of about 150 m with a trundle wheel to a wall; Have a student make a loud sound and start the timer; Stop the timer on hearing the echo; speed = distance x 2 / time

Question 20

Describe a method to measure the speed of sound in air inside the laboratory.

Answer 20

Have two microphones about 2 metres apart; measure with a ruler; connect microphones to a smart timer and make a loud sound near one of the microphones; Timer stops when second microphone detects the sound; Use speed = distance / time