One idea — draw light as a straight line with an arrow — and everything else in the chapter follows from it. Eight lessons, eight labs, a chapter map, and thirty questions.
A model is a scientific representation of something. The ray model represents light as a straight line with an arrow on it — the line shows the path, the arrow shows the direction of travel.
Meets a mirror → it bounces off (reflection). Meets a rough surface → each ray still bounces, but in scattered directions. Meets glass or water → it bends (refraction). Bends by different amounts for different colours → it splits (dispersion).
So there is very little to memorise. What earns the marks is drawing the line correctly and saying what happened to it — which is exactly what the labs here let you practise.
This is scoped for G3. The textbook marks i = r, the whole of refraction and the whole of dispersion as optional for G2. For you they are core — and together they are nearly half the chapter.
The three-card experiment that proves light travels in straight lines — slide a card out of line and watch the flame vanish.
Start → Lesson 2Luminous and non-luminous objects, and the question that catches everyone: can you see a white ball in a totally dark room?
Start →Same size, upright, virtual, laterally inverted, equally far behind. Raise your right hand and see which hand the image raises.
Start → Lesson 4Incident ray, normal, point of incidence, reflected ray — and the rule i = r, on a protractor you can drag.
Start → Lesson 5Concave curves inwards and converges; convex curves outwards and diverges. Dentists, headlights, road junctions and rear-view mirrors.
Start → Lesson 6Why you see yourself in a mirror but not in paper — and why i = r is still true on a rough surface.
Start →Why a pencil looks bent and a pool looks shallow, the cart-on-grass model, and how a prism splits white light into seven colours.
Start → Lesson 8Infrared, ultraviolet and visible light — thermal cameras, sterilisation, vitamin D, skin cancer, light pollution and turtle hatchlings.
Start →Every definition, the image characteristics, both reflection tables, the refraction rules and all the radiation applications.
Open → PracticeLabel a ray diagram, type angles, sort applications — every wrong answer explains itself.
Practice → Challenging · Lvl 2Twenty harder questions with the options set deliberately close together — only correct reasoning separates them.
Take it on →