Modern Physics 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.

Frames & transformations

• Galilean, Lorentz and Adding velocities screens. Click the ground track to make a flash; the readings show (x, t) and (x′, t′).
• In Lorentz, the train ruler is contracted and the train clocks run slow and out of step.

Time dilation

• Light clock: compare tick counts of the resting and moving clocks.
• Muon decay: raise v/c and watch more muons reach the ground.

Length contraction

• Set the speed and rest length; the ship's length along the motion shrinks, its height does not.

Mass & energy

• Relativistic mass: press Restart to push again. E = mc²: pick a mass. Energy–momentum: choose electron or photon and drag pc.

Photoelectric effect

• Pick a metal, set wavelength, brightness and collector voltage. Switch the graph between K_max–f and current–voltage.

Compton effect

• Set the X-ray wavelength and scattering angle; the bars compare λ and λ′ to scale.

Matter waves & quantum

• de Broglie: choose a particle and voltage (or speed). Bohr orbit: set n; only whole numbers fit. Uncertainty: squeeze Δx and watch Δp widen.

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).