Use a sharp pencil and a ruler. Draw light rays as straight ruled lines with an arrow showing direction, and normals as dashed lines at 90° to the surface. Tap 🔍 See examples to see how the diagram usually looks – pictures online vary, so if one disagrees with the instructions, follow the instructions. ← All key diagrams
67. Transverse wave
Draw a horizontal dashed line (the rest position). Draw a smooth wave going above and below it for two full wavelengths. Label: “crest”, “trough”, “amplitude” (from the rest line to a crest), “wavelength” (crest to crest), and an arrow along the line labelled “direction of energy transfer”. Add a vertical double-headed arrow labelled “oscillations at 90° to the energy transfer”.
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68. Longitudinal wave on a slinky
Draw a long row of vertical lines to represent the coils of a slinky. Draw some sections with the lines close together and some with them spread apart. Label: “compression” (close together), “rarefaction” (spread apart), “wavelength” (from one compression to the next). Add a horizontal double-headed arrow labelled “oscillations parallel to the energy transfer”.
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69. Ripple tank practical
Draw a shallow tray of water from the side. Draw a lamp above it and a white screen or sheet of paper below it. Draw a wooden bar (dipper) touching the water surface, attached to a motor connected to a power supply. Label: lamp, ripple tank, water, vibrating bar, motor (sets the frequency), screen showing the wave pattern. Write: “measure across 10 waves to find the wavelength”.
🔍 See examples · 📋 Required practical page
70. Waves on a string practical
Draw a vibration generator on the left connected to a signal generator. Draw a string running from the vibration generator over a wooden bridge and a pulley on the right, with masses hanging on the end. Draw the string as a standing wave with loops. Label: signal generator (sets frequency), vibration generator, string, wooden bridge, pulley, masses, and “wavelength = length of two loops”.
🔍 See examples · 📋 Required practical page
71. Reflection ray diagram (S only)
Draw a horizontal line for a plane mirror and shade short diagonal lines on the back. Draw a dashed normal at 90° to the mirror. Draw an incident ray with an arrow hitting the mirror where the normal meets it, and a reflected ray leaving on the other side of the normal. Label: “incident ray”, “reflected ray”, “normal”, “angle of incidence i”, “angle of reflection r”, “i = r”.
🔍 See examples · 📋 Required practical page
72. Refraction through a glass block
Draw a rectangle for the glass block. Draw a ray entering the top surface at an angle, with a dashed normal. Show the ray bending towards the normal inside the block, then bending away from the normal as it leaves the bottom surface (with a second dashed normal). Label: “slows down – bends towards the normal”, “speeds up – bends away from the normal”, “emerging ray is parallel to the incident ray”.
🔍 See examples · 📋 Required practical page (S only)
73. Wavefronts and refraction (HT)
Draw a diagonal boundary line between “air” and “glass”. In the air, draw evenly spaced parallel lines (wavefronts) approaching the boundary. In the glass, draw the wavefronts closer together and at a different angle. Draw an arrow at 90° to the wavefronts on each side showing the direction. Label: “this end of the wavefront enters the glass first and slows down”, “wavefronts closer together – shorter wavelength”, “wave changes direction”.
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74. The electromagnetic spectrum
Draw a long rectangle divided into seven boxes: radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma. Draw an arrow underneath pointing right labelled “frequency and energy increase” and an arrow pointing left labelled “wavelength increases”. Under each box, write one use. Above the boxes, write “all transverse, all travel at 3 × 10⁸ m/s in a vacuum”.
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75. Convex lens – real image (S only)
Draw a horizontal principal axis and a vertical convex lens symbol (a line with arrowheads pointing outwards). Mark the principal focus F on both sides. Draw an upright object arrow further than 2F from the lens. Draw ray 1 parallel to the axis, then through F on the far side. Draw ray 2 straight through the centre of the lens. Where the rays cross, draw the image. Label: “real, inverted, smaller”.
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76. Convex lens as a magnifying glass (S only)
Draw the same lens and axis, but put the object arrow between F and the lens. Draw ray 1 parallel to the axis then through F, and ray 2 through the centre. The rays spread apart, so extend them backwards as dashed lines until they meet on the same side as the object. Draw the image there with a dashed arrow. Label: “virtual, upright, magnified”.
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77. Concave lens (S only)
Draw a concave lens symbol (a line with arrowheads pointing inwards) on a principal axis, and mark F on both sides. Draw an object arrow on the left. Draw ray 1 parallel to the axis, then spreading out as if it came from F on the left – show this with a dashed line back to F. Draw ray 2 straight through the centre. Where the dashed line and ray 2 meet, draw the image. Label: “virtual, upright, smaller”.
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78. Specular and diffuse reflection (S only)
Draw two surfaces side by side. On the left, a smooth straight line with three parallel rays coming in and three parallel rays reflecting out – label “specular reflection from a smooth surface: clear image”. On the right, a jagged bumpy line with three parallel rays coming in and reflecting out in different directions – label “diffuse reflection from a rough surface: scattered, no image”.
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79. Colour filters (S only)
Draw white light (arrows labelled R, G, B) hitting a red filter. Show only the R arrow coming out of the other side, and cross out the G and B arrows at the filter. Label: “a red filter transmits red light and absorbs the other colours”. Underneath, draw the red light hitting a blue object and write “the object absorbs red – it looks black”.
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80. How we hear (S only, HT)
Draw a simple cross-section of an ear: the ear canal, the eardrum, and the small bones behind it. Draw a longitudinal wave (lines close together and spread out) travelling into the ear canal. Label: “sound wave”, “eardrum vibrates”, “vibrations passed to small bones and the inner ear”, “only works from 20 Hz to 20 kHz”.
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81. Ultrasound echo sounding (S only)
Draw a ship on the surface of the sea and the sea bed below. Draw a pulse of ultrasound going down from the ship with an arrow, and a reflected pulse coming back up. Label: “transmitter”, “receiver”, “sea bed”, “depth = (speed × time) ÷ 2 – the pulse travels there and back”.
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82. Seismic waves through the Earth (S only)
Draw a large circle for the Earth with two circles inside it: the outer core and the inner core. Mark an earthquake at the top. Draw curved P-wave paths passing through the core and S-wave paths stopping at the outer core. Shade the region on the opposite side where no S-waves arrive. Label: “P-waves – longitudinal, travel through solids and liquids”, “S-waves – transverse, solids only”, “S-wave shadow zone – evidence the outer core is liquid”.
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83. Leslie cube practical
Draw a cube from above, showing its four sides labelled: matt black, shiny black, matt white, shiny silver. Show hot water inside. Draw an infrared detector facing one side at a marked distance (e.g. 10 cm). Label: “Leslie cube”, “hot water”, “infrared detector”, “same distance for every side”. Write: “matt black emits the most infrared; shiny silver emits the least”.
🔍 See examples · 📋 Required practical page
84. Black body radiation curves (S only)
Draw axes with “wavelength” on the x-axis and “intensity” on the y-axis. Draw three hump-shaped curves for three temperatures. Make the hottest curve the tallest, with its peak furthest to the left (shortest wavelength). Label the curves “hottest”, “medium” and “coolest”. Write: “hotter objects emit more radiation and the peak wavelength is shorter”.
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Check your drawings: Waves topic page | Refraction | Lenses and visible light | Teach the topic: Waves
