The rival theories of light, how Young’s double-slit experiment shows light is a wave, why diffraction of light is not normally seen, and rays, shadows, eclipses and the pinhole camera.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Is light a stream of tiny particles or a wave? For three hundred years the best scientists disagreed, until one experiment with two slits changed the argument.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Particle (corpuscle) theory of light.
Wave theory of light.
Double-slit interference showed light is a wave.
Photons: light has both wave and particle nature.
Bright = constructive; dark = destructive.
Not normally seen because the wavelength is much smaller than everyday gaps.
Straight lines show the direction of travel; shadows and eclipses show this.
Inverted real image; h_i/h_o = v/u.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Physics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (14 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [14 marks]
A student carries out Young’s double-slit experiment using red light and observes bright and dark fringes on a screen.
(a) (a) State the names of the scientists who proposed a particle theory and a wave theory of light. [2]
(b) (b) Describe what the student sees on the screen. [2]
(c) (c) Explain how a dark fringe is formed. [2]
(d) (d) Explain why this experiment shows that light is a wave. [2]
(e) (e) Explain why diffraction of light is not normally noticed in everyday life. [2]
(f) (f) State what Einstein’s work suggested about light in the twentieth century. [1]
(g) (g) A pinhole camera is 12 cm long. A tree 6.0 m tall is 30 m from the pinhole. Calculate the height of the image. [3]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.