Physics Exam — Sound, Electromagnetic Spectrum, Reflection and Refraction
Explore the world of waves: how sound propagates (why there is no sound in space), frequency and amplitude, the speed of light, mirror reflection, refraction in lenses and prisms, the visible and electromagnetic spectrum, ultrasound and why the sky is blue.
Physics & Chemistry · Primary & Secondary
Sound is a mechanical wave needing a medium (≈ 340 m/s in air). Light is an electromagnetic wave requiring no medium (300,000 km/s in a vacuum). In space, explosions are silent — but light from them reaches us.
Reflection: angle of incidence = angle of reflection (mirrors). Refraction: light changes direction when entering a denser medium — the basis of lenses, glasses, magnifying glasses and rainbows.
From most to least energy: gamma → X-ray → UV → visible → infrared → microwave → radio. Higher frequency = higher energy (E = h × f). Only visible light (400–700 nm) can be seen with the eye.
"A Year 6 student is puzzled why a straw looks bent in a glass of water. The exam explains refraction — and connects it to how glasses correct short-sightedness."
Tricks and techniques to master this topic faster:
Spectrum mnemonic (violet→red): ROY G BIV reversed — violet has the shortest wavelength, red the longest.
Sound speed in air ≈ 340 m/s. Lightning trick: count seconds after a flash, divide by 3 = km away.
Ultrasound: any sound above 20,000 Hz (human upper limit). Bats use it to navigate; doctors use it to scan.
Total internal reflection: the basis of fibre optic cables — light bounces inside glass with zero loss.
If you are studying Waves and Light, these curriculum topics complement each other:
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