Reflection

📋 Teacher notes

• •The law of reflection: the angle of incidence equals the angle of reflection (∠i = ∠r), both measured from the NORMAL — never from the mirror surface itself.
• •The incident ray, the reflected ray, and the normal all lie in the SAME plane — a detail examiners sometimes ask for directly.
• •A plane mirror image is: the same size as the object, the same distance behind the mirror as the object is in front, upright, and VIRTUAL (light doesn’t actually pass through it — it only appears to come from there).
• •Lateral inversion: left and right are swapped (not up and down) — why text held up to a mirror reads backwards, and why an ambulance often has "AMBULANCE" printed mirror-reversed on the front so drivers read it correctly in their rear-view mirror.
• •A plane mirror image cannot be captured on a screen (it’s virtual) — this is the standard way exams distinguish a real image from a virtual one.