---
title: "Waves, Light & Sound"
description: "58 topics in Science, in the order they build on each other."
canonical: https://lightmysky.com/learn/science/areas/waves-light-and-sound
source: https://lightmysky.com/learn/science/areas/waves-light-and-sound.md
retrieved: 2026-10-19
---

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# Waves, Light & Sound

58 topics in Science, in the order they build on each other.

Page: https://lightmysky.com/learn/science/areas/waves-light-and-sound

- [Light & sound vocabulary](https://lightmysky.com/learn/science/light-and-sound-vocabulary-mt_YPSx5pbpVl): Name and use vocabulary for how light and sound behave: light source, transparent, translucent, opaque, shadow, reflect, vibration, pitch and volume. Use these terms correctly to describe observations of how light travels and how sounds are made and changed.
- [Light & seeing in the dark](https://lightmysky.com/learn/science/light-and-seeing-in-the-dark-mt_4i-FKXDDXh): Observe that objects in darkness can be seen only when illuminated by a light source
- [Vibrations & sound](https://lightmysky.com/learn/science/vibrations-and-sound-mt_VBl1T1sFCM): Understand that vibrating materials can make sound, and that sound can make materials vibrate
- [Communication with Light & Sound](https://lightmysky.com/learn/science/communication-with-light-and-sound-mt_ZL9qVVnpwN): Design and build a device that uses light or sound to solve the problem of communicating over a distance
- [Protecting Eyes from Sunlight](https://lightmysky.com/learn/science/protecting-eyes-from-sunlight-mt_3yuqKww2tU): Recognise that light from the sun can be dangerous and that there are ways to protect eyes
- [Reflecting light](https://lightmysky.com/learn/science/reflecting-light-mt_gLy3ZgZWiN): Notice that surfaces reflect light, and that smooth, shiny surfaces can form clear reflected pictures while rough surfaces scatter reflected light
- [Pitch of Sounds](https://lightmysky.com/learn/science/pitch-of-sounds-mt_KTSoXcO7OL): Find patterns between the pitch of a sound and features of the object that produced it
- [Sound travels through materials](https://lightmysky.com/learn/science/sound-travels-through-materials-mt_ydtcIBwHB9): Recognise that vibrations from sounds travel through a medium (solid, liquid, or gas) to the ear
- [Sound Fading with Distance](https://lightmysky.com/learn/science/sound-fading-with-distance-mt_Pau0aqLNgp): Recognise that sounds get fainter as the distance from the sound source increases
- [Volume & Vibrations](https://lightmysky.com/learn/science/volume-and-vibrations-mt__00ZSLnB7p): Find patterns between the volume of a sound and the strength of the vibrations that produced it
- [Wave Behaviour Vocabulary](https://lightmysky.com/learn/science/wave-behaviour-vocabulary-mt_SFOSbVnrJ8): Use technical vocabulary for wave behaviour — refraction, absorption, reflection, scattering, amplitude, frequency, wavelength, echo, spectrum, angle of incidence, angle of reflection — and apply these when explaining how light and sound travel and interact with different materials
- [Waves & how they move](https://lightmysky.com/learn/science/waves-and-how-they-move-mt_ph4xZVMiVq): Develop a model of waves to describe patterns in terms of amplitude and wavelength, and understand that waves can cause objects to move
- [Patterns & Codes for Information](https://lightmysky.com/learn/science/patterns-and-codes-for-information-mt_n5_Jt4ExUd): Generate and compare multiple solutions that use patterns to transfer information, such as codes and signals
- [Wave properties & types](https://lightmysky.com/learn/science/wave-properties-and-types-mt_LxK9OKZQZX): Describe waves in terms of amplitude, wavelength, frequency, and wave speed; distinguish transverse waves (oscillation perpendicular to direction of travel) from longitudinal waves (oscillation parallel); and use the wave equation v = fλ
- [Analog and Digital Signals](https://lightmysky.com/learn/science/analog-and-digital-signals-mt_gg5-bUckYX): How information travels as signals in waves: analog signals vary continuously while digital signals encode information as patterns of on/off pulses, and digitised signals can be copied, stored and sent with far less loss and noise
- [How Sound Waves Travel](https://lightmysky.com/learn/science/how-sound-waves-travel-mt_DQk9oDE7gr): Explain that sound is produced by vibrating objects and travels as a longitudinal pressure wave through solids, liquids, and gases; describe reflection of sound (echoes) and absorption; explain why sound cannot travel through a vacuum
- [The wave equation](https://lightmysky.com/learn/science/the-wave-equation-mt_wmKhTiXt1p): Wave speed equals frequency times wavelength. Use the equation in either direction for sound, ripples and light. To measure speed, time or count real events, such as ripples crossing a tank or an echo returning.
- [Ultrasound and Echo Sounding](https://lightmysky.com/learn/science/ultrasound-and-echo-sounding-mt_nE1uPfjhX-): Sound above the range a person can hear reflects at a boundary between two materials, and timing the return gives the depth of that boundary. The same measurement images a fetus, finds a crack in a casting and maps a sea floor.
- [Progressive waves: phase and path difference](https://lightmysky.com/learn/science/progressive-waves-phase-and-path-difference-mt_RotpycCNF8): Read stated displacement-distance and displacement-time data, calculate phase differences on a periodic progressive wave, and relate path difference to arrival phase for initially in-phase waves of common frequency and wavelength with no additional phase shifts.
- [Polarisation as Evidence for Transverse Waves](https://lightmysky.com/learn/science/polarisation-as-evidence-for-transverse-waves-mt_mCbxv77qDA): Linear polarisation restricts transverse oscillations to one direction. Ideal crossed polarising filters block light. Longitudinal sound in air cannot be polarised; optical filters are not a test for sound.
- [Superposition and Stationary Waves](https://lightmysky.com/learn/science/superposition-and-stationary-waves-mt_AIxA2TYGJN): In a linear wave model, overlapping displacements add point by point. Equal sinusoidal waves travelling in opposite directions can form stationary nodes and antinodes. A uniform string fixed at both ends supports harmonics with neighbouring nodes half a wavelength apart.
- [Coherence and Young's Double-Slit Fringes](https://lightmysky.com/learn/science/coherence-and-youngs-double-slit-fringes-mt_mONvXhPmwq): Coherent waves have the same frequency and a fixed phase difference. For initially in-phase, matching-polarisation slit outputs, whole-wavelength path differences give constructive interference. Near the centre of a distant screen, fringe spacing is approximately w = lambda D/s.
- [The Diffraction Grating and Measuring Wavelength](https://lightmysky.com/learn/science/the-diffraction-grating-and-measuring-wavelength-mt_yIjB-uJuFt): For normally incident coherent monochromatic light in the far field, a grating's principal reinforcement directions satisfy d sin(theta) = n lambda, with theta measured from the grating normal. Many illuminated slits make narrow principal maxima useful for wavelength measurement.
- [Single-Slit Diffraction and the Limit of Resolution](https://lightmysky.com/learn/science/single-slit-diffraction-and-the-limit-of-resolution-mt_qiG0fGadBU): In far-field single-slit diffraction, a narrower slit or longer wavelength broadens the central maximum. Two finite slits add interference fringes within a diffraction envelope. For an ideal diffraction-limited instrument, a larger aperture reduces the angular resolution threshold.
- [Normal Modes of a Bounded System](https://lightmysky.com/learn/science/normal-modes-of-a-bounded-system-mt_650O-YrqJs): Fixing the ends of a string or closing a pipe allows only those wavelengths that fit, so the system rings at a fundamental and its harmonics. Which harmonics appear is set by the boundary conditions.
- [The Doppler Effect and Shock Waves](https://lightmysky.com/learn/science/the-doppler-effect-and-shock-waves-mt_UVfD_coqh6): Motion of the source or the observer changes the observed frequency, with the two cases giving different formulas that agree at low speed. When the source outruns its own waves the fronts pile into a cone.
- [The Wave Equation and Its Travelling-Wave Solutions](https://lightmysky.com/learn/science/the-wave-equation-and-its-travelling-wave-solutions-mt_Ue-v1cSxNx): Any function of x minus vt keeps its shape while moving, and the second-order equation relating the curvature of a wave to its acceleration is what such functions satisfy. One equation covers strings, sound and light.
- [Wave Speed on a String from Tension and Linear Density](https://lightmysky.com/learn/science/wave-speed-on-a-string-from-tension-and-linear-density-mt_83x7vwb7UU): The speed of a wave on a stretched string comes from the restoring tension and the inertia per unit length, with no reference to how the wave was made. Tuning an instrument is a change to one of those two quantities.
- [Intensity: the Energy and Power Carried by a Wave](https://lightmysky.com/learn/science/intensity-the-energy-and-power-carried-by-a-wave-mt_Hj-yG6g3CD): A wave carries power proportional to the square of its amplitude, and intensity is that power spread over area. Spreading in three dimensions is why intensity falls with the square of the distance.
- [Phasor Addition and the Mathematics of Interference](https://lightmysky.com/learn/science/phasor-addition-and-the-mathematics-of-interference-mt_dxh7HHbIUw): Representing each contributing wave as a rotating arrow turns interference into vector addition, so intensity comes from the length of the resultant. Two-slit, multi-slit and single-slit patterns all follow from the same picture.
- [Thin-Film Interference and Anti-Reflection Coatings](https://lightmysky.com/learn/science/thin-film-interference-and-anti-reflection-coatings-mt_3ugW-ZijzH): Light reflected from the two faces of a thin film interferes, and whether the result is bright or dark depends on the film thickness and on a phase change at reflection. Lens coatings are that condition engineered on purpose.
- [Intensity in Single-Slit and Double-Slit Diffraction](https://lightmysky.com/learn/science/intensity-in-single-slit-and-double-slit-diffraction-mt_HURhzZdIkM): Continuous phasor addition gives the far-field intensity of a uniformly illuminated slit. For two identical slits under coherent monochromatic normal illumination with common polarisation, the single-slit envelope multiplies the interference factor. Their overlap can suppress an otherwise allowed interference order.
- [The Michelson Interferometer](https://lightmysky.com/learn/science/the-michelson-interferometer-mt_Wlb1tZnJBi): Splitting a beam and recombining it after two paths turns a tiny difference in path length into a countable shift of fringes. The instrument measures displacement in units of the wavelength of its own light.
- [X-Ray Diffraction and the Bragg Condition](https://lightmysky.com/learn/science/x-ray-diffraction-and-the-bragg-condition-mt_qEDplGeIkB): X-rays scattered by a crystal interfere at angles satisfying the Bragg condition. Reflection positions constrain atomic plane spacings, while intensities provide further structural information. Analysis of X-ray patterns helped reveal crystal structures and DNA's double helix.
- [Transparent, Translucent & Opaque](https://lightmysky.com/learn/science/transparent-translucent-and-opaque-mt_p6frRFuxS6): Investigate the effect of placing objects made of different materials in the path of a beam of light, discovering transparent, translucent, and opaque materials
- [How Shadows Form](https://lightmysky.com/learn/science/how-shadows-form-mt_Oru08pKlxd): Recognise that shadows are formed when light from a source is blocked by an opaque object, and find patterns in how shadow size changes
- [How we see objects](https://lightmysky.com/learn/science/how-we-see-objects-mt_6w2g7aoPgz): Develop a model to describe that light reflecting from objects and entering the eye allows objects to be seen
- [Light travels in straight lines](https://lightmysky.com/learn/science/light-travels-in-straight-lines-mt_qZro923zvz): Use straight-ray models for light travelling through uniform air in classroom situations, and explain shadows as projections made when opaque objects block light
- [Reflection & Refraction](https://lightmysky.com/learn/science/reflection-and-refraction-mt_PifbJOuXrG): State the law of reflection (angle of incidence = angle of reflection), explain how light changes speed when crossing between materials, and predict whether its direction changes; use ray diagrams for flat mirrors and describe ray paths at air-water or air-glass boundaries
- [White Light & Colour](https://lightmysky.com/learn/science/white-light-and-colour-mt_qzGADV-NGe): Explain that white light is a mixture of all visible colours (ROYGBIV), describe dispersion through a prism, explain why objects appear coloured (selective reflection and absorption of wavelengths), and describe colour mixing with filters
- [Drawing Ray Diagrams](https://lightmysky.com/learn/science/drawing-ray-diagrams-mt_-2VNlwAR5z): Draw ray diagrams to show reflection at a plane mirror (angle of incidence = angle of reflection) and refraction at a boundary between media; use ray diagrams to locate images and explain how lenses and mirrors work
- [Ray Diagrams & Images](https://lightmysky.com/learn/science/ray-diagrams-and-images-mt_FVERuBoCD1): Construct ray diagrams to show the formation of images by plane mirrors and converging lenses, identifying whether images are real or virtual, magnified or diminished, upright or inverted
- [The Electromagnetic Spectrum](https://lightmysky.com/learn/science/the-electromagnetic-spectrum-mt_XSp-S0wter): Describe the full electromagnetic spectrum from radio waves to gamma rays, in order of increasing frequency and energy; explain that all EM waves travel at the same speed in a vacuum; and describe the uses and hazards of different regions
- [Waves & Different Materials](https://lightmysky.com/learn/science/waves-and-different-materials-mt_w5HzPpOUmj): Explain how waves can be absorbed, transmitted, or reflected by different materials, and apply these interactions to explain colour perception, sight, communication technologies, and the effects of different surfaces on wave behaviour
- [Refraction and lenses](https://lightmysky.com/learn/science/refraction-and-lenses-mt_u8GKuBMmzC): Explain transmitted light at stationary boundaries using changes in speed and wavelength at fixed frequency. Use ideal converging-lens ray diagrams to locate and describe images, and explain total internal reflection in fibres.
- [Huygens's Principle and the Laws of Reflection and Refraction](https://lightmysky.com/learn/science/huygenss-principle-and-the-laws-of-reflection-and-refraction-mt_xxdniF2__w): Treating every point on a wavefront as a source of new wavelets reproduces reflection and refraction without any new assumption. Snell's law becomes a statement about wave speed in each material.
- [Thin Lenses and the Lens Maker's Equation](https://lightmysky.com/learn/science/thin-lenses-and-the-lens-makers-equation-mt_FXOcC5mpIM): Refraction at two curved surfaces gives a focal length set by the curvatures and the refractive index, and the thin lens equation then locates any image. Sign conventions carry most of the difficulty.
- [Curved Mirrors, the Mirror Equation and Real Images](https://lightmysky.com/learn/science/curved-mirrors-the-mirror-equation-and-real-images-mt_7XqB2umthJ): A concave mirror brings parallel light to a focus at half its radius of curvature, and one equation then locates the image for any object distance. Sign conventions decide whether the image is real or virtual, upright or inverted, and they are where most of the difficulty sits.
- [Magnifiers, Microscopes and Telescopes](https://lightmysky.com/learn/science/magnifiers-microscopes-and-telescopes-mt_f30rUsqYkN): Instruments are built by putting lenses in sequence so that the image of one becomes the object of the next, and angular magnification is what the eye actually notices. A telescope trades field of view for resolution and light collected.
- [Total Internal Reflection, Optical Fibres and Dispersion](https://lightmysky.com/learn/science/total-internal-reflection-optical-fibres-and-dispersion-mt_ZNSZMLkOD_): Past the critical angle light cannot leave a dense material at all, which is what keeps a signal inside a fibre. Because refractive index depends on wavelength, a prism spreads white light and a long fibre smears a pulse.
- [The Electromagnetic Spectrum: Uses and Dangers](https://lightmysky.com/learn/science/the-electromagnetic-spectrum-uses-and-dangers-mt_P_NXNSo1zQ): The seven groups run from radio waves to gamma rays in order of increasing frequency, all travelling at the same speed through space. Each group has uses that follow from how it interacts with matter, and the high-frequency end is ionising.
- [Infrared Emission, Absorption and the Temperature of a Body](https://lightmysky.com/learn/science/infrared-emission-absorption-and-the-temperature-of-a-body-mt_xwh9uZ8gCl): Ordinary objects above absolute zero emit thermal radiation. Emission depends on temperature and surface properties. Controlled comparisons of matt black paint and polished metal show how surfaces affect radiative heating and cooling. Earth's average temperature also depends on absorbed sunlight and thermal radiation escaping to space.
- [Photon Energy and the Electronvolt](https://lightmysky.com/learn/science/photon-energy-and-the-electronvolt-mt_UfmDhGRaYT): Light delivers energy in packets of size hf, so the energy of a photon is fixed by its frequency alone. The electronvolt is the convenient unit at that scale: the energy one electron gains crossing one volt.
- [The Photoelectric Effect and the Work Function](https://lightmysky.com/learn/science/the-photoelectric-effect-and-the-work-function-mt_ADQK7WB2JN): Electrons leave a metal surface only above a threshold frequency, however bright the light gets, which no wave picture accounts for. One photon frees one electron, giving hf equal to the work function plus the greatest kinetic energy.
- [Energy Levels and Line Spectra](https://lightmysky.com/learn/science/energy-levels-and-line-spectra-mt_RlMCSDxE5q): An atom holds only certain electron energies, so a jump between two of them emits or absorbs a photon of one exact energy. That is why a hot gas gives bright lines and a cool gas in front of a lamp gives dark ones.
- [de Broglie Waves and Electron Diffraction](https://lightmysky.com/learn/science/de-broglie-waves-and-electron-diffraction-mt_Y8NthsmPcv): If light can behave as particles then particles can behave as waves, with wavelength h divided by momentum. Electrons fired at a thin crystal give diffraction rings, which nothing but a wave can produce.
- [Fourier Analysis and the Wave Packet](https://lightmysky.com/learn/science/fourier-analysis-and-the-wave-packet-mt_1ZaojWUZEw): Piecewise smooth periodic signals have Fourier series with a mean and harmonic sine and cosine terms. Isolated pulses have continuous frequency spectra. Compressing a fixed pulse shape in time widens its frequency spread.
- [Stimulated Emission and How a Laser Works](https://lightmysky.com/learn/science/stimulated-emission-and-how-a-laser-works-mt_xgjD0mzEAV): An excited atom hit by a photon of the right energy emits a second identical photon, and a population inversion plus a mirrored cavity turns that into a beam. Coherence, not brightness, is what separates a laser from a lamp.