Static Electricity 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.

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.

Coulomb's law

• Two charges: set q₁, q₂ and r; the equal and opposite force arrows, attraction or repulsion, F = kq₁q₂/r².
• In a medium: the same pair in paper, glass or water and the fall by κ.
• Three charges: the net force on the middle charge by superposition.

Electric field

• Field lines: traced for one charge, a dipole, two like charges and two plates.
• Field of a point charge: E = kq/r² with the 1/r² graph.
• Uniform field: an electron or proton accelerating between two plates, E = V/d, a = qE/m, W = qV.

Gauss's law

• Electric flux: turn a loop in a field; Φ = EA cos θ.
• Choosing a Gaussian surface: spherical, cylindrical and planar symmetry side by side — which parts of the surface have E ⟂ (flux EA) and which have E ∥ (flux 0), with the numbered steps.
• Point charge: sphere: E × 4πr² = q/ε₀ and Coulomb's law falling out.
• Line charge: cylinder: a coaxial cylinder round a long wire, flux only through the curved side, E = λ/2πε₀r with the 1/r graph.
• Plane sheet: pillbox: a pillbox through a sheet, both end caps, E = σ/2ε₀ at any distance.
• Two plates & conductors: superposing two sheets (σ/ε₀ between, zero outside) or a pillbox on a metal surface; V = Ed and C = ε₀A/d.
• Charged sphere: conducting (E = 0 inside) or uniformly charged insulating (E = kQr/R³ inside), kQ/r² outside, with the graph.

Electric potential

• Point charge: V = kq/r, equipotential circles, the 1/r graph.
• Moving a charge: W = q₀ΔV between two radii, sign and meaning.
• Equipotentials: contour maps for a charge, a dipole and two plates with the field lines crossing at right angles.

Capacitors

• Parallel plates: C = κε₀A/d with area, gap, dielectric and voltage; charge flowing on from the battery, field lines and E = V/d.
• Dielectric: air and dielectric side by side with the polarised molecules and induced charges; battery connected (V fixed) or removed (Q fixed) — what happens to C, Q, V, E and U.
• Series & parallel: charges and voltages on each capacitor.
• Energy stored: the Q–V triangle, U = ½CV² and the energy density.
• Charging through R: the RC circuit charging or discharging, V_C and I against t/τ, τ = RC, 63 % after one τ.

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