GCSE Waves Revision: Wave Speed, Properties, Required Practical Links, and Exam Questions

Overview

This section gives you the core knowledge to return to quickly. If your revision feels scattered, start here and make sure each point is secure before moving on to exam questions.

For strong GCSE waves revision, you should be able to answer five basic questions without hesitation:

1. What is a wave?
2. What is transferred by a wave?
3. What is the difference between transverse and longitudinal waves?
4. What do amplitude, wavelength, frequency, and period mean?
5. How do you use the wave speed equation correctly?

A wave is a way of transferring energy from one place to another without transferring matter overall. That idea matters because exam questions often test whether you know that the medium may vibrate or oscillate, but it does not travel along with the wave.

In properties of waves GCSE physics questions, these definitions are the ones to know clearly:

• Amplitude: the maximum displacement from the rest position.
• Wavelength: the length of one complete wave, for example from crest to crest or compression to compression.
• Frequency: the number of waves passing a point each second, measured in hertz, Hz.
• Period: the time taken for one complete wave.
• Wave speed: the speed at which the wave travels through a medium or space.

You should also remember the two main wave types:

• Transverse waves: oscillations are perpendicular to the direction of energy transfer. Light and other electromagnetic waves are transverse. Water waves are often treated as transverse at GCSE level.
• Longitudinal waves: oscillations are parallel to the direction of energy transfer. Sound waves are longitudinal.

The key equation is:

wave speed = frequency × wavelength

Written with symbols:

v = fλ

This is the central wave speed equation GCSE students need for calculations. Learn the units as part of the formula:

• v in metres per second, m/s
• f in hertz, Hz
• λ in metres, m

A simple worked example:

A wave has frequency 5 Hz and wavelength 2 m.

v = fλ = 5 × 2 = 10 m/s

Always write the substituted numbers into the equation before the final answer. That helps with method marks and makes checking easier.

You should also know the link between frequency and period:

frequency = 1 / period

or

f = 1 / T

This often appears in combined questions where you may need one equation before using another.

Finally, connect waves to familiar GCSE topics:

• Sound links to hearing, ultrasound, and echoes.
• Light links to the electromagnetic spectrum, reflection, and refraction.
• Wave calculations connect to broader equation skills across the course. If you need a refresher on formula use, see GCSE Physics Equations List: What You Need to Memorise and How to Use Each Formula.

Checklist by scenario

Use this section as a practical revision tool. Different wave questions require different habits, so revise by scenario rather than by reading notes passively.

1. If you are learning the basic theory of waves

• Can you define a wave as energy transfer without overall transfer of matter?
• Can you distinguish transverse and longitudinal waves?
• Can you identify crests, troughs, compressions, and rarefactions from a diagram?
• Can you define amplitude, wavelength, frequency, and period accurately?
• Can you name at least one transverse and one longitudinal wave?

A useful self-test is to sketch one transverse wave and one longitudinal wave, then label wavelength and amplitude where possible. If you cannot label your own diagram, revisit the definitions before moving on.

2. If you are revising calculations

• Write down v = fλ from memory.
• Check that frequency is in Hz and wavelength is in metres.
• Rearrange only if needed: f = v / λ and λ = v / f.
• Show substitution clearly.
• Give the final answer with units.

Example:

A sound wave travels at 340 m/s and has a frequency of 170 Hz. Find the wavelength.

λ = v / f = 340 / 170 = 2 m

Students often lose marks not because the physics is difficult, but because they drop units or misread the value they need to calculate.

If equation work across the course feels shaky, it can help to revise this alongside motion formulas in GCSE Forces and Motion Revision: Distance-Time Graphs, Speed, Velocity, and Acceleration.

3. If you are answering diagram or description questions

• Check whether the question is asking about the wave itself or the particles in the medium.
• For transverse waves, describe vibrations at right angles to energy transfer.
• For longitudinal waves, describe vibrations parallel to energy transfer.
• Use the correct vocabulary: oscillate, compressions, rarefactions, crest, trough, amplitude, wavelength.

These questions reward precise language. Short answers are often best. A one-sentence definition with the right terms usually scores more reliably than a longer vague explanation.

4. If you are preparing for required practical waves GCSE work

Many specifications include wave-related practical skills, especially measuring wave speed on water, strings, or using ripple tanks, and work involving reflection, refraction, or sound. The exact classroom method can vary, so focus on the underlying method rather than memorising a single script.

Checklist for a typical waves practical:

• Know the aim: for example, measuring wave speed or observing wave behaviour.
• Identify the independent, dependent, and control variables.
• Know the equipment and why each item is used.
• Take repeat readings where possible.
• Measure carefully from the same reference points each time.
• Record values with units in a sensible table.
• Calculate mean values if appropriate.
• Use the relevant equation after measurements are complete.
• Comment on errors, uncertainty, and improvements.

For example, if measuring wave speed in a ripple tank or on a string, you may measure wavelength from several waves at once and divide by the number of waves. This often reduces percentage uncertainty compared with measuring one short distance.

A strong physics practical write up for waves usually includes:

• a clear method in logical order
• labelled results table
• sample calculation
• brief conclusion linked to data
• evaluation of likely errors and realistic improvements

If you are building exam technique for longer written responses, see How to Answer 6 Mark Physics Questions: A GCSE and A-Level Exam Technique Guide.

5. If you are revising wave behaviours

Do not stop at the equation. GCSE waves revision also includes what waves do.

• Reflection: a wave bounces off a surface.
• Refraction: a wave changes direction when it enters a different medium because its speed changes.
• Absorption: wave energy is taken in by the material.
• Diffraction: waves spread out after passing through a gap or around an obstacle.

These ideas are often tested with diagrams. If a wave enters a new medium and slows down, the wavelength changes too. Frequency stays the same because it is set by the source. That is a common exam point.

6. If you are doing exam questions under time pressure

• Underline the command word: calculate, describe, explain, compare, suggest.
• Circle the values and units given.
• Check whether you need one step or more than one.
• For explanation questions, use cause-and-effect wording.
• For comparison questions, make both sides of the comparison clear.

In waves exam questions GCSE papers, many marks are lost through rushed reading. A student may know the topic well but still answer about amplitude when the question asked about wavelength, or write about speed when the mark scheme wanted frequency.

7. If you want a short final checklist before a test

• I can define a wave.
• I know transverse vs longitudinal.
• I can label amplitude and wavelength.
• I know v = fλ.
• I can rearrange the equation.
• I can use units correctly.
• I understand reflection and refraction.
• I can describe a simple waves practical.
• I can spot common errors in a graph or table.
• I can explain my method clearly in a longer answer.

For wider topic planning, use GCSE Physics Topics List with Revision Priority, Key Equations, and Common Mistakes.

What to double-check

This is the section to use right before homework submission, a practical write-up, or an exam paper.

• Units: Is wavelength in metres, not centimetres, unless converted first?
• Equation choice: Are you using wave speed, not a formula from a different topic?
• Definitions: Are you describing energy transfer rather than matter transfer?
• Wave type: Have you matched transverse or longitudinal correctly?
• Frequency and period: Have you reversed them accidentally?
• Diagram reading: Are you measuring one full wavelength, not half?
• Practical variables: Have you identified what is changed, measured, and controlled?
• Graph interpretation: If the question includes a graph, are you taking values carefully from the axes?

If your question mixes waves with electricity, sound, or communication systems, slow down and identify which topic each part belongs to. Cross-topic questions can feel harder than they are. If you need support with electrical formulas and comparisons, see GCSE Electricity Revision: Equations, Circuits, Power, and Resistance.

Common mistakes

These are the errors that come up again and again in GCSE waves revision and in class assessments.

Confusing amplitude and wavelength

Amplitude is the height from the middle to the crest or trough. Wavelength is the horizontal distance of one complete wave. If you are unsure, redraw the wave and mark the rest position first.

Forgetting that frequency stays the same at a boundary

When a wave moves from one medium to another, speed may change and wavelength may change, but frequency stays the same because the source does not change.

Using the wrong units

If wavelength is given in cm, convert to m before using the standard equation unless the entire calculation is being handled consistently. Most GCSE questions expect SI units.

Describing particles as travelling with the wave

In many wave models, particles oscillate around a fixed position. Energy moves, but the material does not move overall from source to receiver.

Writing vague practical evaluations

“Human error” on its own is too vague. Better examples are: difficulty identifying the exact wave crest, reaction time when timing oscillations, or parallax when reading a ruler. A good improvement matches the problem directly.

Not reading the command word

A “calculate” question needs working. A “describe” question needs observable features. An “explain” question needs a reason using physics ideas. Match your answer type to the command word.

Leaving answers without units

Even when the number is correct, missing units can cost marks or make an answer incomplete. Build the habit of writing them every time.

When to revisit

Waves is worth revisiting more than once because different parts become important at different stages of the course. Keep this checklist and return to it when one of these situations applies.

• Before starting required practical work: review variables, measurements, and common evaluation points.
• Before mocks or end-of-topic tests: focus on definitions, diagrams, and the wave speed equation GCSE students use most often.
• When your class begins sound or light: revisit transverse and longitudinal waves, plus reflection and refraction.
• When you notice repeated calculation mistakes: come back to unit conversion and equation rearrangement.
• When exam questions feel inconsistent: practise by scenario rather than rereading notes.

A practical way to use this guide is to split your revision into three short passes:

1. First pass: learn the definitions and draw the diagrams.
2. Second pass: do five to ten calculation questions using v = fλ.
3. Third pass: answer one practical method question and one explanation question.

If you are revising digitally, combine this guide with active recall and past-paper practice rather than scrolling through notes. For planning your wider revision sessions, you may also find Past-Paper Strategy for Digital Exams: How to Prepare When Questions Feel More Interactive useful.

Your next action can be simple: write the three key definitions from memory, complete two wave speed calculations, and explain one waves practical method in six clear steps. If you can do those accurately, your waves revision is moving in the right direction.