Geometrical Optics Lab

Everywhere

• Topic tabs (under the title) switch between simulations in this lab. Some topics have smaller buttons under the stage for their screens.
• Teach shows live equations with the current numbers and "What to notice" points. Practice gives a numeric problem and a quiz.
• Move the sliders or tap the chips in the right-hand panel. The readings box updates live.
• Pause / Restart control the animation. Clean view hides everything except the stage, for projecting or recording; press Esc to leave it.
• In Practice, type a number (e.g. 12.5 or 3.2e-10), press Check or Enter. Show it on the stage sets the simulation to that problem.
• Nothing is saved: scores reset when the page is reloaded.

Eight topics along the top

• Mirrors: plane (image as far behind as the object is in front, and the half-height rule), concave and convex with the three standard rays, 1/v + 1/u = 1/f and f = R/2. Cartesian signs throughout: u < 0 for a real object.
• Refraction: Snell's law at a plane surface with any pair of media, the glass slab with its lateral shift d = t sin(i − r)/cos r, and apparent depth — a coin seen from above (real depth / n) and a bird seen from under water (n × real height).
• Total internal reflection: sweep i past the critical angle and watch the refracted ray vanish; the optical fibre with core, cladding, acceptance angle and numerical aperture; and the 45° reflecting prism turning light through 90° or 180°.
• Spherical surface: n₂/v − n₁/u = (n₂ − n₁)/R with a signed radius.
• Thin lenses: ray diagrams for convex and concave lenses, the lens-maker's formula with two signed radii (and what happens in water), power in dioptres and two lenses in contact.
• Prism: the ray through both faces with the i–δ curve and δₘ; dispersion of white light through crown or flint glass, with the spread exaggerated on request.
• Instruments: magnifying glass (M = 1 + D/f or D/f), compound microscope and astronomical telescope with the tube length and magnifying power.
• The eye: a reduced eye with its accommodation range, then myopia and hypermetropia — see the image miss the retina, then switch the correcting lens on and read its power.

Teach and Practice

• Teach shows the equations with your numbers and notes for each view. Practice gives a numerical problem for the current view — Check the answer, Show it on the stage, or ask for a New problem — plus a quick-check quiz.

Language

• Choose English or বাংলা once on the home page (top right); every lab then opens in that language — tabs, controls, readings, equations, notes, problems and quizzes.

Full guide with teaching tips: User manual (also as a PDF).