Pro Tip: Don't just memorize — understand each formula. Click the "Practice on Simulator" links to see every formula come to life interactively. Visual understanding = better retention for boards.
Chapter 1
Electric Charges & Fields
⚡ Practice on Electric Field Simulator →
| Formula | Name | Variables |
|---|---|---|
| F = kq₁q₂/r² | Coulomb's Law | k = 9×10⁹ N·m²/C², q = charges, r = distance |
| E = F/q = kQ/r² | Electric Field | E in N/C, Q = source charge |
| E = σ/ε₀ | Field — infinite sheet | σ = surface charge density |
| φ = E·A·cosθ | Electric Flux | φ in N·m²/C |
| φ = q/ε₀ | Gauss's Law | Total flux = enclosed charge/ε₀ |
| p = q·d | Electric Dipole Moment | Direction: –q to +q |
| τ = pE·sinθ | Torque on Dipole | Max when θ = 90° |
Chapter 2
Electrostatic Potential & Capacitance
🔋 Practice on Capacitor Simulator →
| Formula | Name | Variables |
|---|---|---|
| V = kQ/r | Electric Potential | V in volts, r = distance from charge |
| W = q·V | Work Done | Moving charge q through potential V |
| C = Q/V | Capacitance | C in Farad (F) |
| C = ε₀A/d | Parallel Plate Capacitor | A = area, d = separation |
| U = ½CV² = Q²/2C | Energy Stored | U in Joules |
| C_series = (1/C₁ + 1/C₂)⁻¹ | Series Combination | Total C decreases |
| C_parallel = C₁ + C₂ | Parallel Combination | Total C increases |
Chapter 3
Current Electricity
💡 Practice on Circuit Simulator →
| Formula | Name | Variables |
|---|---|---|
| V = IR | Ohm's Law | V = voltage, I = current, R = resistance |
| R = ρL/A | Resistance | ρ = resistivity, L = length, A = area |
| P = VI = I²R = V²/R | Power | P in Watts |
| R_series = R₁ + R₂ + ... | Series Resistors | Current same in all |
| 1/R_parallel = 1/R₁ + 1/R₂ | Parallel Resistors | Voltage same across all |
| E = I(R + r) | EMF equation | r = internal resistance of cell |
| I = nAeVd | Drift Velocity | n = electron density, Vd = drift velocity |
Chapter 4
Moving Charges & Magnetism
🧲 Practice on Magnetic Field Simulator →
| Formula | Name | Variables |
|---|---|---|
| F = qv×B = qvBsinθ | Lorentz Force (magnetic) | F on moving charge in field B |
| F = IL×B = BILsinθ | Force on Current Wire | L = length of wire in field |
| r = mv/qB | Radius of circular motion | Charge moving perpendicular to B |
| B = μ₀I/2πr | Field near long wire | μ₀ = 4π×10⁻⁷ T·m/A |
| B = μ₀nI | Solenoid field | n = turns per unit length |
| τ = nIAB·sinθ | Torque on current loop | n = turns, A = area |
Chapter 6
Electromagnetic Induction
🔄 Practice on EM Induction Simulator →
| Formula | Name | Variables |
|---|---|---|
| φ = NBA·cosθ | Magnetic Flux | N = turns, B = field, A = area |
| ε = –dφ/dt | Faraday's Law (EMF) | Induced EMF = –rate of change of flux |
| ε = BLv | Motional EMF | Conductor moving in field |
| ε = –L·dI/dt | Self Induction | L = self-inductance in Henry |
| U = ½LI² | Energy in Inductor | U in Joules |
Chapter 9
Ray Optics & Optical Instruments
🔭 Practice on Lens Formula Simulator →
| Formula | Name | Variables |
|---|---|---|
| 1/f = 1/v – 1/u | Mirror Formula | Sign convention: distances from pole |
| 1/f = 1/v – 1/u | Lens Formula | f = focal length, v = image, u = object distance |
| m = v/u = h'/h | Magnification | m = –ve → inverted image |
| P = 1/f(m) | Power of Lens | P in Dioptre (D), f in metres |
| n = c/v = sinᵢ/sinᵣ | Snell's Law / RI | n = refractive index |
| sinC = 1/n | Critical Angle | For total internal reflection |
| 1/f = (n–1)(1/R₁ – 1/R₂) | Lensmaker's Equation | R₁, R₂ = radii of curvature |
Chapter 11
Dual Nature of Radiation & Matter
☀️ Practice on Photoelectric Effect Simulator →
| Formula | Name | Variables |
|---|---|---|
| E = hf = hc/λ | Photon Energy | h = 6.626×10⁻³⁴ J·s, c = 3×10⁸ m/s |
| KE_max = hf – φ | Einstein's Photoelectric | φ = work function |
| eV₀ = hf – φ | Stopping Potential | V₀ = stopping voltage |
| λ = h/mv = h/p | de Broglie Wavelength | p = momentum |
| p = h/λ = E/c | Photon Momentum | c = speed of light |
Chapter 13
Nuclei
⚛️ Practice on Nuclear Decay Simulator →
| Formula | Name | Variables |
|---|---|---|
| N = N₀·e^(–λt) | Radioactive Decay Law | λ = decay constant, N₀ = initial nuclei |
| t½ = 0.693/λ | Half-Life | Time for half the nuclei to decay |
| BE = (Zm_p + Nm_n – M)·c² | Binding Energy | Mass defect × c² |
| R = R₀·A^(1/3) | Nuclear Radius | R₀ = 1.2×10⁻¹⁵ m, A = mass number |
| E = mc² | Mass-Energy Equivalence | Einstein's famous equation |