Waves Basics

Question 1

Describe, generally, what waves do.

Answer 1

They transfer energy in the direction they are travelling without transferring matter

Question 2

Waves can be either transverse or longitudinal.

State one similarity between longitudinal and transverse waves.

Answer 2

Any one from:

• They both transfer energy but not matter
• They both have a wavelength/frequency/speed

Question 3

Describe one difference between longitudinal and transverse waves.

Answer 3

• In transverse waves, the vibrations are perpendicular to the direction the wave travels
• In longitudinal waves, the vibrations are parallel to the direction the wave travels

Question 4

Give some examples of transverse waves.

Answer 4

• All electromagnetic waves
• S-waves (a seismic wave)
• Ripples and waves in water

Question 5

Give some examples of longitudinal waves.

Answer 5

• Sound waves
• P-waves (a seismic wave)

Question 6

(Exam-style question)

Explain, with evidence, that with sound waves it’s the wave and not the air itself that travels.

Answer 6

• When sound waves move through the air to a person’s ear, the air itself does not move
• Sound is transferred via vibrating particles, which stay where they are and vibrate about a fixed point - our eardrums vibrate with the particles

Question 7

(Exam-style question)

Ripples pass a leaf on a pond after a child throws a stone into it.

Explain why the ripples do not carry the leaf to the edge of the pond.

Answer 7

• Although the ripples travel across the pond, the water just travels up and down
• Therefore, the ripples cannot move the leaf across the pond

Question 8

Recall the parts of a transverse wave on a diagram.

Answer 8

Question 9

What is meant by the term ‘frequency’?

Answer 9

The number of complete cycles of a wave passing a certain point per second

(1Hz is 1 wave per second)

Question 10

What is meant by the term ‘wavelength’?

Answer 10

The length of a full cycle of a wave

(e.g. from crest to crest, or from compression to compression)

Question 11

What is the equation to calculate the speed of a wave?

Answer 11

Question 12

What is meant by the ‘amplitude’ of a wave?

Answer 12

The displacement from the rest position to a crest or trough

Question 13

What is meant by the ‘period’ of a wave?

Answer 13

The time taken for a full cycle of the wave to pass a point

(Period = 1 ÷ frequency)

Question 14

What is meant by the term ‘wavefront’?

Answer 14

The front of the wave, or the same point on each wave

(this tends to be the crest or peak of the wave)

Question 15

What is meant by the term ‘wave velocity’?

Answer 15

The speed at which a wave moves through a space