Why does your twin walk too? Light did not copy you — it only bounced. Move the ray below; wonder first, then the why.
Predict ∠r, lock it, then dial ∠i and watch the bounce. Plane / concave / convex · formula for curved · ∠i–∠r graph. 🟢 real reflection engine
Guess, then change ∠i — the bounce waits until you commit.
Set the mirror and ∠i — the reflected ray must match ∠r = ∠i from the normal.
Aim the incident ray. The bounce obeys ∠i = ∠r. Can you hit the amber target in 3 attempts?
Drag the aim, then fire. Physics decides the bounce — not hope.
Each diagram breaks one law. Tap the broken idea. Expert thinking starts when something looks almost right.
On a smooth mirror ∠i must equal ∠r from the normal. 30° in and 50° out cannot happen.
Plane-mirror images of real objects are virtual — rays diverge. A screen behind the glass stays dark.
For a real object, a convex (diverging) mirror only makes a diminished upright virtual image — never a real inverted one on a card.
Thinking beats memorising. Sort the universe of mirrors into three boxes.
Incident ray and normal are fixed. Drag your reflected aim. Grade when you think ∠r matches the law.
Set the bounce yourself — the engine grades honesty, not hope.
Pick a job. Dial kind, |u| and |f|. The formula tells you if you built the right tool.
For a shaving mirror: concave, object inside the focus → virtual, upright, |m| > 1.
No upload needed — read the scene. What mirror (and image behaviour) is at work?
Concave + object inside focus → virtual, upright, magnified — makeup/shave territory.
Convex shrinks the scene for field of view — smaller look → brain thinks farther.
A flat water surface behaves like a huge plane mirror when calm — virtual twin below; wind → diffuse scatter.
This page covers the law of reflection (∠i = ∠r), plane mirrors, concave and convex spherical mirrors, the mirror formula 1/v + 1/u = 1/f, and magnification m = −v/u. By the end you'll be able to:
Mirrors open every light chapter — and "reflection of light" / spherical mirrors is a core Class 8–10 topic on every board. We go beyond the syllabus, but we never skip it:
Searched as: law of reflection, angle of incidence, plane mirror, concave convex mirror, 1/v + 1/u = 1/f, magnification, image distance.
Your twin walked back because the bounce law is mercilessly fair: whatever angle arrived, the same angle left. Curve the glass and the meeting place of the rays — the image — shifts. Same law. New geography.
Reflection is light bouncing off a boundary. Draw a dashed normal at right angles to the surface. The angle of incidence (∠i) and angle of reflection (∠r) are both measured from that normal — and they are equal. A plane bathroom mirror, a spoon, and a car wing mirror all obey the same bounce rule.
A plane mirror puts a virtual image as far behind as the object is in front, same size, upright. A concave (converging) mirror can form real inverted images or magnified virtual faces for shaving. A convex (diverging) mirror always gives a smaller upright virtual image — wide field for traffic. The maths link is 1/v + 1/u = 1/f with f = R/2.
The Rays tab eases the incident ray to your chosen ∠i and mirrors the bounce so ∠r matches (motion-feel). Switch Plane / Concave / Convex, set |u| and |f|, and readouts follow the formula. The ∠i–∠r tab is a straight diagonal — the law drawn as a graph. 🟡 maths of the picture
Exams reward the method, not just the answer. Work it out one step at a time — read the thought, predict the line, then reveal it. Switch to practice to type your own numbers and check them.
Drag the numbers — watch ∠r, v and m update.
Sticky wrong ideas about reflection deserve their own warning label. Tap a card to bust the myth.
Same bounce law. Wilder tools. Civilization is a gallery of mirrors.
Status and ritual first — a face in metal taught ∠i = ∠r long before symbols for it.
Tin behind glass democratises the twin. Bathrooms are just late arrivals.
Newton’s reflector sidesteps colour fringes — concave gatherer + flat tip.
Dental folds, shop domes, sun furnaces — applied bounce everywhere.
Orbiting concave systems and golden hexes — 1/v + 1/u at cryogenic scale.
The brain meets fair physics and calls it magic. Each trick is still ∠i = ∠r (or a stack of them).
A tilted pane mixes a reflected performer with the live stage — virtual image overlapping real space.
Two facing mirrors trap ray after ray; your eyes invent a tunnel of twins.
Corridors of planes kill your sense of depth — every exit is a law repeated.
A curved or angled reflection “decrypts” a warped painting into a sharp face.
Eighteen hex mirrors align so starlight acts like one giant concave collector — the same 1/v + 1/u geometry, just colder and farther than any bathroom glass.
A tilted sheet of glass mixes a reflected actor with the real stage — your brain meets a ghost that is only ∠i = ∠r in theatre clothing.
Laser scanners time bounced pulses; dentists fold sight with tiny planes; solar furnaces aim sunbeams with hills of mirrors — civilization is applied reflection.
Once humans could polish curves and silver glass, they built telescopes, headlights, scanners and surveillance that all start from ∠i = ∠r.
Drag the ladder — everyday mirrors that still obey ∠i = ∠r.
Shape changes; ∠i = ∠r stays the habit.
Physics you can see. Each project shows reflection — and the measuring is what turns a demo into a science-fair winner.
Build: stand a pin in front of a plane mirror on paper; sight and mark incident and reflected rays with another pin.
Measure: angles from a drawn normal — they should match within a few degrees.
Build: look into both sides of a polished spoon.
Measure: which side magnifies close-up? Which shrinks and widens the room?
Build: place an object at measured u from a plane mirror; use parallax or a second object behind a clear board to find image position.
Measure: image distance ≈ u — as far behind as in front.
Build: a concave makeup mirror, a candle beyond f, a white card.
Measure: where a sharp inverted flame appears — that is a real image you can catch.
Build: compare how much of a room a phone selfie camera sees via a plane vs a convex door mirror.
Measure: count distinct objects visible — convex should win on width.
Build: focus a distant window on a screen with a concave mirror; distance mirror-to-screen ≈ f.
Measure: several trials, average f, then compare with an estimate from a measured radius if you can.
Mirrors look simple until the first ray diagram. Straight answers:
The angle of incidence equals the angle of reflection, and both are measured from the normal — a line perpendicular to the surface at the hit point. The incident ray, reflected ray and normal also lie in one plane.
Angles measured along the glass confuse every diagram. The normal gives a fair, shared zero so ∠i and ∠r can be compared fairly on curved mirrors too — draw it at the point of incidence.
No — it is virtual. Reflected rays diverge into your eyes as if they came from a spot behind the glass; nothing meets on a screen there. Real images form when rays actually converge and can light a card.
When the object is between the pole and the focus, the image is virtual, upright and enlarged — the shaving-mirror case. Beyond the focus you get real inverted images whose size depends on exact u.
It links object distance u, image distance v and focal length f for spherical mirrors (with a chosen sign convention). Know two, solve for the third. Schools usually use the New Cartesian signs.
Convex mirrors shrink the scene (|m| < 1) so cars look smaller and farther than they are. The warning reminds you the geometry traded size for a wider field of view.
For a spherical mirror under the usual school approximation, the focal length is half the radius of curvature: f = R/2. The focus sits midway from the pole to the centre of curvature.
Reflection bounces light back into the original medium (∠i = ∠r). Refraction is light entering a new medium and usually bending (Snell's law). Most boundaries do a bit of both; mirrors are built to favour the bounce.
Spot these before the exam does.
Seven question formats, the way LLOS.ai serves them — multiple choice, multiple-correct, fill-in-the-blank, match, sequence, read-think-connect, and write-your-own. Every question has layered hints: a quick nudge, the reasoning, then a deeper connection — so a wrong answer opens a door, never a dead end. 🟢 received from a board-tagged question bank · seed toward 2,000
Pick your board — the set re-tunes to its wording and emphasis. Competitive draws the JEE / NEET / Olympiad lane.
A mirror never invents light — it only keeps the promise that whatever angle arrives, the same angle leaves.