Log In
Log In
Led by James Clerk Maxwell Simulacrum
Six tutorials covering AQA GCSE Physics §4.6 Waves — wave properties, reflection and detection, the electromagnetic spectrum, refraction and radiation hazards, lenses and colour, and black body radiation — taught by simulacra of the physicists who worked out how waves carry energy through the universe.
Courses are available to holders of a paid pass or membership. See passes & membership →
Led by Joseph Fourier Simulacrum
The question
What is a wave, what does it carry, and what are the four numbers that tell you everything you need to know about any periodic wave?
Territory
waves transport energy, not matter · evidence: ripples on water, sound waves in air · transverse waves (disturbance perpendicular to travel) · longitudinal waves (disturbance along travel, compressions and rarefactions) · amplitude (maximum displacement from undisturbed position) · wavelength (distance between corresponding points on adjacent waves) · frequency (waves per second, in hertz) · period T = 1/f · wave speed v · the wave equation v = fλ · identifying amplitude and wavelength from diagrams · methods to measure speed of sound in air and of ripples on water · (physics only) changes in v, f, and λ when a wave crosses between media (f stays constant, v and λ change together) · required practical 8 (ripple tank and waves in a solid — frequency, wavelength, speed)
Outcome
The student can distinguish transverse from longitudinal waves with examples, define amplitude, wavelength, frequency, and period, apply T = 1/f and v = fλ, measure these quantities in a ripple tank, and (physics only) reason about what changes when a wave crosses from one medium to another. (AQA 4.6.1.1, 4.6.1.2)
Led by Christiaan Huygens Simulacrum
The question
What happens when a wave meets a boundary, how does a sound wave become a vibration you hear, and how do we see inside an object with ultrasound?
Territory
reflection at boundaries between materials · absorption and transmission · ray diagrams for reflection · effects of reflection, transmission, and absorption at material interfaces · required practical 9 (reflection and refraction of light) · (HT) sound waves causing vibrations in the eardrum and solids · (HT) why frequency conversion between sound and solid vibration is limited · (HT) human hearing range 20 Hz–20 kHz · (HT) ultrasound (above 20 kHz) · (HT) partial reflection at media boundaries · (HT) time-of-flight distance measurement · (HT) medical and industrial imaging applications · (HT) seismic waves: P-waves (longitudinal, through solids and liquids) and S-waves (transverse, solids only) · (HT) evidence for Earth's core structure from P- and S-wave travel · (HT) echo sounding in deep water
Outcome
The student can construct ray diagrams for reflection, describe what happens at material boundaries, (HT) describe how sound is converted to mechanical vibration, state the human hearing range, explain ultrasound imaging, and use P- and S-wave properties to reason about the Earth's interior. (AQA 4.6.1.3, 4.6.1.4, 4.6.1.5)
Led by James Clerk Maxwell Simulacrum
The question
Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays — what do all these have in common, and what distinguishes them?
Territory
electromagnetic waves are transverse · all EM waves travel at the same velocity through vacuum (or air) · the EM spectrum as a continuous spectrum · seven named groups from long to short wavelength (equivalently, low to high frequency): radio, microwave, infrared, visible light (red through violet), ultraviolet, X-rays, gamma rays · our eyes detect only visible light · EM waves transfer energy from source to absorber · practical applications: radio (TV, radio), microwaves (satellite comms, cooking), infrared (heaters, cooking, thermal imaging), visible light (fibre-optic communications), ultraviolet (energy-efficient lamps, sun-tanning), X-rays and gamma rays (medical imaging and treatments) · (HT) why each type of wave is suited to its application
Outcome
The student can name the seven groups of the EM spectrum in order of wavelength or frequency, state that all EM waves are transverse and travel at the same speed through vacuum, identify a practical application for each group, and (Higher Tier) explain why the wavelength makes it suitable for that application. (AQA 4.6.2.1, 4.6.2.4)
Led by William Herschel Simulacrum
The question
When a ray of light passes from air into water it bends — why? And when ultraviolet or X-ray radiation passes through your skin, why is that genuinely dangerous?
Territory
(HT) different substances absorb, transmit, refract, or reflect EM waves with wavelength-dependent behaviour · (HT) refraction arising from change in wave speed between media · (HT) ray diagrams for refraction · (HT) wavefront diagrams explaining refraction · (HT) radio waves from oscillations in electrical circuits · (HT) radio waves inducing alternating current in an aerial at the same frequency · gamma rays from changes in atomic nuclei · hazards of UV, X-rays, gamma rays · dose measured in sieverts (recall of unit not required) · UV: premature skin ageing, skin cancer · X-rays and gamma rays: ionising, can mutate genes and cause cancer · risk-versus-benefit evaluation from given data · required practical 10 (how infrared absorption and emission depend on surface nature)
Outcome
The student can explain that different wavelengths interact with matter differently, (HT) explain refraction using ray and wavefront diagrams, describe the biological hazards of UV, X-rays, and gamma rays, evaluate risk from quantitative data, and carry out Required Practical 10. (AQA 4.6.2.2, 4.6.2.3)
Led by Pierre de Fermat Simulacrum
The question
How does a lens form an image, and what actually determines the colour you perceive when you look at an object?
Territory
a lens forms an image by refraction · convex lens brings parallel rays to the principal focus · focal length as distance from lens to principal focus · real vs virtual images (convex can produce either; concave always virtual) · ray diagrams for convex and concave lenses (with AQA's standard symbols) · magnification = image height / object height (ratio, no units) · image and object heights measured in the same units · each visible colour has its own band of wavelength and frequency · specular reflection (smooth surface, single direction) vs diffuse reflection (rough surface, scattering) · colour filters as wavelength-selective absorbers/transmitters · colour of an opaque object = wavelengths reflected versus wavelengths absorbed · white and black explained by differential reflection · transparent vs translucent objects
Outcome
The student can construct ray diagrams for convex and concave lenses showing real and virtual images, apply the magnification equation, distinguish specular from diffuse reflection, and explain the colour of an opaque object in terms of differential absorption, transmission, and reflection. (AQA 4.6.2.5, 4.6.2.6)
Led by Max Planck Simulacrum
The question
Why does a poker glow red hot, and what does the temperature of the Earth depend on?
Territory
all bodies emit and absorb infrared radiation · hotter bodies radiate more infrared per unit time · perfect black body = absorbs all incident radiation, reflects and transmits none · good absorber = good emitter (perfect black body is most efficient emitter possible) · intensity and wavelength distribution of emission depend on temperature · (HT) object at constant temperature absorbs and emits at equal rates · (HT) temperature rises when absorption rate exceeds emission rate · (HT) temperature of the Earth depends on absorption, emission, and reflection rates · (HT) interpreting diagrams of radiation affecting Earth's surface and atmosphere
Outcome
The student can explain that all bodies emit radiation with intensity and wavelength distribution set by temperature, define a perfect black body, and (Higher Tier) explain how the balance between absorbed and emitted radiation determines the temperature of an object — including the Earth. (AQA 4.6.3.1, 4.6.3.2)