G3 Physics and O-Level Waves Hub
G3 Physics and O-Level Waves hub for wave motion, sound, the electromagnetic spectrum, reflection, refraction, total internal reflection and converging lenses.
Learning goals
- Describe wave generation by vibrating sources, ropes and springs
- Describe ripple-tank waves using wavefronts
- Explain that waves transfer energy
- Explain that wave energy transfer does not transfer matter
- Use amplitude, frequency and wavelength to describe wave motion
- Define and use wave speed and period and interpret wave graphs
- Recall and apply wave speed = frequency × wavelength
- Compare transverse and longitudinal waves and give examples
- Explain sound production by vibration and the need for a medium
- Describe sound using compressions and rarefactions
- Relate sound loudness to amplitude and pitch to frequency
- Explain reflected-sound echoes and use them to measure distance
- Explain ultrasound use in sonar and soft-tissue scanning
- Use the normal, angle of incidence and angle of reflection
- Apply the law of reflection in constructions, measurements and calculations
- Use the normal, angle of incidence and angle of refraction
- Apply sin i divided by sin r as a constant for a fixed pair of media
- Define refractive index as vacuum light speed divided by medium light speed
- Explain the critical angle
- Explain the conditions for total internal reflection
- Apply total internal reflection to optical fibres and state advantages
- Describe how a thin converging lens acts on a light beam
- Define the focal length of a converging lens
- Construct real and virtual image ray diagrams for a thin converging lens
- Describe lens images as real or virtual, magnified or diminished, and upright or inverted
Waves transfer energy without net transfer of matter. This hub moves from general wave properties to sound, the electromagnetic spectrum and light.
Start here
- Wave motion, quantities and wave types
- Ripple-tank measurement
- Sound production and propagation, then loudness, pitch, echoes and ultrasound
- Electromagnetic-wave properties and order, then uses and hazards
- Reflection, refraction and total internal reflection
- Thin converging lenses, then image construction
Use the Waves & Sound Explorer after step 3 and the Light & Lens Explorer after step 6.
What you will learn
The route below keeps closely related ideas together while giving calculations, explanations and ray diagrams enough space to be learnt properly.
Topic 10: General Wave Properties
- Wave motion, ropes, springs, ripple-tank wavefronts, and energy without matter transfer
- Speed, frequency, wavelength, period, amplitude and graph representations
- Applying v = fλ
- Transverse and longitudinal comparison
- Vibrating sound sources, need for a medium, compressions and rarefactions
- Loudness–amplitude and pitch–frequency
- Echoes and distance measurement
- Ultrasound in sonar and medical scanning
Topic 11: Electromagnetic Spectrum
- Transverse nature, common vacuum speed, spectrum order and trends
- Typical uses across all seven regions
- Heating and ionising hazards to cells and tissue
Topic 12: Light
- Reflection terms and i = r
- Refraction terms and sin i/sin r
- Refractive index n = c/v
- Critical angle, total internal reflection and optical fibres
- Converging action and focal length
- Lens ray diagrams and image characteristics
Ripple-tank reflection, refraction and diffraction can strengthen the wave model, but they are not separate requirements here. Learn them as useful enrichment after the core wave quantities and sound ideas are secure.
Lessons
Topic hubs
General Wave Properties Hub
Wave quantities (λ, f, T, v), v = fλ and ripple-tank wavefronts.
Sound Hub
Loudness, pitch, echoes, and ultrasound (longitudinal waves).
Light Hub (Reflection + Refraction)
Reflection, refraction, total internal reflection, and ray diagrams.
Converging Lens Hub
Thin lenses, ray diagrams, and image formation.
General wave properties
Wave Properties
Defining Amplitude, Wavelength, Frequency, and Period.
Ripple Tank
Visualising wavefronts and measuring wavelength and wave speed.
Sound
Production & Propagation
How sound travels via compressions and rarefactions.
Loudness & Pitch
Amplitude affects loudness; Frequency affects pitch.
Echo & Speed of Sound
Echo problems: sound travels there and back (distance = 2d).
Ultrasound
Applications of high-frequency sound (medical, sonar).
Electromagnetic spectrum
Continue to the separate Electromagnetic Spectrum hub. It owns the three spectrum lessons and their completion; this Waves link is supporting navigation only.
Reflection and refraction
What is Light?
Nature of light and its properties.
Reflection
Plane mirrors and ray diagrams (angle of incidence equals reflection).
Refraction
Snell's Law and bending of light.
Total Internal Reflection
Optical fibres and critical angle calculations.
Converging Lenses
Converging action, principal focus, focal length, and safe focal-length measurement.
Converging lenses and image construction
Drawing Ray Diagrams (Mirrors)
Step-by-step guide to sketching mirror ray diagrams.
Ray Diagrams (Lenses)
Predict image position, size, and nature for a converging lens.
Applications of lenses
Transfer core image-characteristic reasoning to cameras, projectors and magnifying glasses.
The applications of converging lenses page provides supplementary device contexts for the core image-characteristics outcome. Lens power and the thin-lens equation belong to later study and are not required here.
Revision
Required relationships and definitions
| Idea | Relationship or test | Exam check |
|---|---|---|
| Period and frequency | T = 1/f | Period uses seconds; frequency uses hertz. |
| Wave speed | v = fλ | Convert wavelength to metres. |
| Echo distance | d = vt/2 | The measured time is for the outward and return path. |
| Reflection | i = r | Both angles are measured from the normal. |
| Refraction | sin i/sin r = constant | Applies to a fixed pair of media and travel direction. |
| Refractive index | n = c/v | Refractive index has no unit. |
| Total internal reflection | higher n to lower n, with i > c | State both conditions. |
Highest-value misconceptions
- A wave transfers energy; particles of a mechanical medium oscillate without net forward transfer.
- Transverse and longitudinal describe oscillation relative to propagation, not whether a drawing is vertical or horizontal.
- A displacement–distance graph and a displacement–time graph do not have interchangeable horizontal axes.
- Loudness relates to amplitude; pitch relates to frequency.
- Ultrasound is mechanical sound, not ionising electromagnetic radiation.
- All electromagnetic waves have the same speed in vacuum; frequency increases as wavelength decreases.
- Reflection and refraction angles are measured from the normal.
- A real lens image comes from actual ray intersections; a virtual image comes from backward extensions.
Practice
- Complete the General Wave Properties check, Electromagnetic Spectrum check and Light check to find the first idea to revisit.
- Use the Waves quiz for retrieval across all three topics.
- Finish with Structured Waves practice for calculations, explanations and ray construction.
Continue learning
Continue to Static Electricity. Return to Measurement if graph axes, units or practical readings are still insecure.
Course and syllabus information
- Course
- SEC G3 Physics
- Edition
- SEC G3 Physics 2027