2.1 Waves
Summary: What do the ripples across a lake and the sound of an elastic band being plucked have in common? They are both waves. But what is a wave? Tags: science oxford-science student-book-7 physics Created: 2026-05-19 Last Updated: 2026-05-19
After this topic, you will be able to:
- describe the properties of waves
- describe how waves are reflected and superpose.
Think back
- Where do you see waves?
- What type of waves can you hear?
- How can you make waves in a bath?
Key idea Waves are oscillations or vibrations that carry Energy. Scientists can measure amplitude, frequency, and wavelength.
Key words oscillation, vibration, energy, undulation, amplitude, frequency, wavelength, peak, crest, trough, transverse, longitudinal, compression, rarefaction, reflection, incident wave, reflected wave, superpose
What do the ripples across a lake and the Sound of an elastic band being plucked have in common? They are both waves. But what is a wave?
What is a wave?
In science, a wave is an oscillation or vibration that transfers energy or information. A wave can also be an undulation on the surface of water. Matter does not get transferred by waves. Waves have many uses. For example, microwaves cook food and sound waves help you communicate.
What are the features of a wave?
All waves have three important features: amplitude, frequency, and wavelength. You can see these in Figure 1.
- Amplitude is the distance from the middle of the wave to the top or bottom of the wave.
- Frequency is the number of waves that pass a particular point per second.
- Wavelength is the distance from one point on a wave to the same point on the next wave.
Figure 1Features of a wave. Full text alternative to the content
A Name two features of a wave you could measure with a ruler.
What are the two types of wave?
You can make waves on a Slinky spring in two different ways.
- You can move your hand at right angles to the spring. This produces a transverse wave (see Figure 2). Figure 2You can make a transverse wave on a Slinky spring. Full text alternative to the content
- You can also push and pull the spring. This produces a longitudinal wave (see Figure 3). There are compressions and rarefactions in a longitudinal wave.
Figure 3You can also make longitudinal waves on a Slinky spring. Full text alternative to the content
Sound waves are longitudinal and Light waves are transverse.
B Explain why waves you make in the bath are transverse.
What happens when waves hit a barrier?
Waves bounce off surfaces and barriers, just like a ball bounces off a wall. Figure 4 shows water waves bouncing off a barrier. This is called reflection.
Figure 4Waves reflect off a barrier. Full text alternative to the content
C State the angle between the direction of travel and the vibrations of particles in a transverse wave.
What happens when waves superpose?
When two waves are put together, they superpose. This means that they add up or cancel out. If the waves are in step, they will add together. You get a single wave with more height than you had before. If they are not in step, then they cancel each other out. The height of the single wave is less than you had before.
Literacy skills Write the word that matches each definition. a) the distance from the peak to the middle of a wave b) where the links of a spring are squashed together
Stretch zone
- Copy and complete the sentences. A wave is an oscillation or vibration that transfers energy/matter. The distance from the centre of the wave to the top of the wave is called the amplitude/wavelength. The distance between one crest of a wave and the next crest is called the amplitude/wavelength. Waves can reflect/superpose when they hit a barrier. When two waves meet each other, they will reflect/superpose.
- Describe the difference between a compression and a rarefaction in a longitudinal wave on a spring.
Stretch zone
- A microwave oven has a plate that turns round a point to move food through areas where microwaves superpose. Suggest what would happen if the plate stops moving.