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ISC Class 12 Physics Formula Sheet 2027: All Nine Units, with Common Traps
This ISC Class 12 Physics formula sheet lists the key formulas and relations for all nine units of the official CISCE ISC 2027 Physics (861) syllabus, in the same order and with the same unit marks. Each unit has a compact table and a short "how to use / common traps" note, because in ISC Physics most marks are lost by applying a correct formula under the wrong conditions. A final table flags formulas that many books and older sheets include but the 2027 Class XII syllabus does not name.
A formula sheet is a revision tool, not a way to learn a unit for the first time. If a unit still feels shaky, one-to-one support from our ISC home tutors in Gurgaon for Class 11 and 12 can rebuild it, and this page then becomes your daily recall tool. For the full topic list behind each unit, read our ISC Class 12 Physics syllabus 2027 guide. The page is built to print cleanly: use your browser's Print option.
How to use this ISC Class 12 Physics formula sheet
Use the sheet for short, daily recall sessions. The unit list and marks below come from the official CISCE ISC Year 2027 Physics (861) syllabus. In Class XII, Paper I (Theory) is 3 hours and 70 marks. Paper II carries 30 marks: Practical 15, Project Work 10 and Practical File 5.
| Unit (ISC 2027 Class XII) | Official weightage | Section on this page |
|---|---|---|
| 1. Electrostatics; 2. Current Electricity | 14 marks (together) | 1 and 2 |
| 3. Magnetic Effects of Current and Magnetism; 4. Electromagnetic Induction and Alternating Currents | 16 marks (together) | 3 and 4 |
| 5. Electromagnetic Waves | 2 marks | 5 |
| 6. Optics | 18 marks | 6 |
| 7. Dual Nature of Radiation and Matter | 7 marks | 7 |
| 8. Atoms and Nuclei | 6 marks | 8 |
| 9. Electronic Devices | 7 marks | 9 |
| Total | 70 marks |
The official ISC 2027 Physics specimen question paper has 20 compulsory questions in four sections: A (14 one-mark parts), B (seven 2-mark questions), C (nine 3-mark questions) and D (three 5-mark questions), with internal choice in two questions each in B, C and D. A simple scientific calculator without programmable memory is allowed.
- Cover and recall. Cover the formula column and write each relation from memory. Anything you miss goes into an error list at the back of your notebook.
- Learn which results you must derive. The syllabus asks you to derive many results (dipole fields, capacitance, drift velocity, mirror and lens formulas, fringe width and others) and to state some as "formula only". The tables mark these where it matters.
- Learn the conditions. "r >> 2l" for a short dipole, "charge constant" or "battery connected" for a dielectric, "small angles" for fringe width. The traps below point these out.
- Units. The syllabus says to use SI units, and to use nm, not Å, for wavelength in atomic spectra.
1. Electrostatics
Here k = 1/4πε0 ≈ 9 × 109 N m2 C−2, and a dipole has charges ±q separated by 2l.
Electric charges and fields
| Result | Formula |
|---|---|
| Coulomb's law | F = k q1q2/r2; in a medium F = q1q2/(4πε0εrr2) |
| Quantisation of charge | q = ne, e = 1.6 × 10−19 C |
| Field and force | E = F/q0; F = qE; point charge E = kq/r2 |
| Dipole moment | p = q × 2l, directed from −q to +q |
| Dipole field, axial (derive) | E = k·2pr/(r2 − l2)2; short dipole E = 2kp/r3 |
| Dipole field, equatorial (derive) | E = kp/(r2 + l2)3/2; short dipole E = kp/r3, opposite to p |
| Dipole in a uniform field (derive) | Net force 0; torque τ = p × E, τ = pE sin θ |
| Electric flux | Φ = E·A = EA cos θ; non-uniform Φ = ∮E·dA |
| Gauss's theorem | ∮E·dA = qenclosed/ε0 |
| Infinite line of charge (λ per metre) | E = λ/(2πε0r) |
| Infinite thin plane sheet (σ per m2) | E = σ/(2ε0), independent of distance |
| Thin spherical shell (charge q, radius R) | Outside (r > R): kq/r2; on the surface: kq/R2; inside: 0 |
Potential, potential energy and capacitance
| Result | Formula |
|---|---|
| Potential of a point charge (derive) | V = kq/r; VA − VB = kq(1/rA − 1/rB) |
| Work and potential | V = W/q0; W = q(VA − VB) |
| Dipole potential (short dipole) | Axial V = kp/r2; equatorial V = 0 |
| System of charges | V = algebraic sum of kqi/ri |
| Potential energy | Two charges U = kq1q2/r; three charges U = k(q1q2/r12 + q1q3/r13 + q2q3/r23) |
| Dipole in a uniform field (derive) | U = −p·E = −pE cos θ; minimum at θ = 0°, zero at 90°, maximum at 180° |
| Capacitance | C = Q/V; parallel plate C = ε0A/d (derive) |
| Combinations | Series 1/C = 1/C1 + 1/C2 + …; parallel C = C1 + C2 + … |
| Energy stored | U = ½CV2 = ½QV = Q2/2C; energy density u = ½ε0E2 |
| Dielectric constant | K = C′/C = εr = ε/ε0; filled capacitor C′ = Kε0A/d |
| Dielectric, battery removed (Q constant) | V′ = V/K; E′ = E/K; energy falls by a factor K |
| Dielectric, battery connected (V constant) | Q′ = KQ; energy rises by a factor K |
| Slab of thickness t partly filling the gap | C′ = ε0A/(d − t + t/K) |
How to use / common traps: the most common slip is using the short-dipole results when the question gives r close to l; check "r >> 2l" before simplifying. Potential is a scalar, so add potentials with their signs, but add fields as vectors. With a dielectric, first ask whether the battery is still connected; the answers go in opposite directions. Example: plates of area 0.02 m2, 4 mm apart, give C = 44.25 pF. Insert a slab 2 mm thick with K = 4 and C′ = ε0A/(0.004 − 0.002 + 0.0005) = 70.8 pF, not K × 44.25 pF, because the slab fills only half the gap. For Gauss's theorem, name the Gaussian surface and say why E is constant over it; the syllabus asks for the "essential properties of a Gaussian surface".
2. Current electricity
| Result | Formula |
|---|---|
| Current and drift velocity (derive) | I = Q/t; I = neAvd; vd = eEτ/m |
| Mobility and current density | μ = vd/E; J = I/A = σE |
| Resistivity from theory (derive) | σ = ne2τ/m; ρ = m/(ne2τ) |
| Ohm's law and resistance | V = IR; R = ρl/A; conductance G = 1/R; conductivity σ = 1/ρ |
| Temperature dependence (standard form) | Rt ≈ R0(1 + αΔT); α > 0 for metals, resistance falls with temperature for semiconductors |
| Energy and power | E = VIt = I2Rt = V2t/R; P = VI = I2R = V2/R; 1 kWh = 3.6 × 106 J |
| Cell with internal resistance | ε = I(R + r); I = ε/(R + r); terminal pd V = ε − Ir |
| n identical cells in series | I = nε/(R + nr) |
| m identical cells in parallel | I = ε/(R + r/m) |
| Mixed grouping (m rows of n cells) | I = nε/(R + nr/m) |
| Two unequal cells in parallel | εeq = (ε1r2 + ε2r1)/(r1 + r2); req = r1r2/(r1 + r2) |
| Kirchhoff's laws | Junction: ΣI = 0 (charge conservation); loop: ΣΔV = 0 (energy conservation) |
| Wheatstone bridge, balanced (derive with Ig = 0) | R1/R2 = R3/R4 |
| Metre bridge | R/S = l/(100 − l), l in cm |
| Potentiometer | V = kl (k = potential gradient); compare emfs ε1/ε2 = l1/l2 |
| Internal resistance by potentiometer | r = R(l1 − l2)/l2 (l1 open circuit, l2 with R connected) |
How to use / common traps: terminal pd equals the emf only when no current flows. Example: a 2 V cell with r = 0.5 Ω across R = 3.5 Ω gives I = 2/4 = 0.5 A and V = 2 − 0.25 = 1.75 V. In Kirchhoff loops, fix one sign rule and keep it: the syllabus uses ΔV = −IR going with the current and +ε going from the negative to the positive terminal. A potentiometer's sensitivity improves with a smaller potential gradient, which means a longer wire, not a bigger driving cell. In the potentiometer internal-resistance method, l1 is the open-circuit balance length; with l1 = 60 cm, l2 = 50 cm and R = 10 Ω, r = 10 × 10/50 = 2 Ω. Swapping l1 and l2 gives a negative resistance, which should warn you at once.
From our tutors: in electrostatics and circuits, ISC students rarely forget the formula itself. What costs marks is a missing condition or a missing diagram: the Gaussian surface not drawn, the short-dipole step not justified, or a Kirchhoff loop with no marked current directions. When a student in our sessions writes a relation, we ask for one line saying when it is valid. The habit takes a week to build and saves marks in every derivation.
3. Magnetic effects of current and magnetism
| Result | Formula |
|---|---|
| Biot–Savart law | dB = (μ0/4π) I dl × r̂ / r2; μ0 = 4π × 10−7 T m A−1 |
| Centre of a circular loop, N turns (derive) | B = μ0NI/2r |
| On the axis of a loop (derive) | B = μ0NIr2/[2(r2 + x2)3/2] |
| Finite straight wire (formula only) | B = (μ0I/4πd)(sin α + sin β) |
| Ampere's circuital law | ∮B·dl = μ0I; long straight wire B = μ0I/2πr; long solenoid B = μ0nI (n = turns per metre) |
| Force on a moving charge (Lorentz force) | F = q(E + v × B); magnetic part F = qvB sin θ |
| Circular path in a uniform B (follows from F = qvB) | r = mv/qB; T = 2πm/qB |
| Force on a conductor | F = I l × B; F = BIl sin θ |
| Two long parallel wires (derive) | F/l = μ0I1I2/2πd; attract for like currents; defines the ampere |
| Torque on a current loop (derive) | τ = NIAB sin θ; τ = m × B with m = NIA (A m2) |
| Orbital magnetic moment of an electron (Bohr model) | m = evr/2 |
| Moving coil galvanometer | I = kθ, k = c/NAB; current sensitivity θ/I = NAB/c; voltage sensitivity θ/V = NAB/(cG) |
| Galvanometer to ammeter (range I) | Shunt S = IgG/(I − Ig) in parallel |
| Galvanometer to voltmeter (range V) | Series R = V/Ig − G |
| Bar magnet fields (no derivation) | End-on B = (μ0/4π)(2m/r3); broadside-on B = (μ0/4π)(m/r3) |
| Magnetic flux | Φ = B·A = BA cos θ; unit weber; 1 T = 104 gauss |
| Magnetic materials | H = B/μ0 − M; χm = M/H; μr = 1 + χm |
| Dia, para, ferro | χm small and negative (μr < 1); small and positive (μr > 1); very large (μr >> 1) |
| Curie's law (paramagnets) | χm ∝ 1/T; a ferromagnet becomes paramagnetic above its Curie temperature |
How to use / common traps: B at the centre of a loop has 2r in the denominator, while B near a long wire has 2πr; mixing them is the classic slip. Example: 100 turns of radius 5 cm carrying 0.5 A give B = (4π × 10−7 × 100 × 0.5)/(2 × 0.05) ≈ 6.28 × 10−4 T. For galvanometer conversions, the ammeter shunt is tiny and in parallel, the voltmeter resistance is large and in series: with G = 50 Ω and Ig = 5 mA, a 0–5 A ammeter needs S ≈ 0.050 Ω and a 0–10 V voltmeter needs 1,950 Ω. The syllabus uses the right-hand thumb rule only ("no other rule necessary"), and the bar-magnet field formulas are to be stated, not derived. In the B–H loop, retentivity and coercivity are qualitative only.
4. Electromagnetic induction and alternating currents
Electromagnetic induction
| Result | Formula |
|---|---|
| Faraday's and Lenz's laws | ε = −N dΦ/dt; the induced current opposes the change that causes it |
| Motional emf (rod length l, speed v) | ε = Blv; power dissipated P = (Blv)2/R |
| Self-induction | Φ = LI; ε = −L dI/dt; 1 henry = 1 V s A−1 |
| Long solenoid (N turns, length l) | L = μ0N2A/l = μ0n2Al |
| Mutual induction | Φ2 = MI1; ε2 = −M dI1/dt |
| Two coaxial solenoids | M = μ0N1N2A/l = μ0n1N2A |
| Ideal transformer | Vs/Vp = Ns/Np = Ip/Is; efficiency = output power/input power |
| AC generator | ε = NBAω sin ωt; peak ε0 = NBAω |
Alternating current
| Result | Formula |
|---|---|
| RMS and mean values (sinusoidal only) | Irms = I0/√2 ≈ 0.707 I0; mean over a half cycle = 2I0/π ≈ 0.637 I0; mean over a full cycle = 0 |
| Pure R, L, C (V = V0 sin ωt) | R: I in phase; L: I lags V by π/2; C: I leads V by π/2 |
| Reactances | XL = ωL = 2πfL (rises with f); XC = 1/ωC = 1/2πfC (falls with f) |
| Series LCR (phasor method) | V2 = VR2 + (VL − VC)2; Z = √[R2 + (XL − XC)2] |
| Phase angle | tan φ = (XL − XC)/R; I = I0 sin(ωt − φ); I0 = V0/Z |
| Power | P = VrmsIrms cos φ = ½V0I0 cos φ = Irms2R; power factor cos φ = R/Z |
| Resonance | XL = XC; Z = R (minimum); ω0 = 1/√(LC); f0 = 1/(2π√(LC)) |
| Q factor and bandwidth (no derivation) | Q = ω0L/R = (1/R)√(L/C); bandwidth Δω = R/L = ω0/Q |
| Wattless current | Pure L or pure C (cos φ = 0) gives P = 0; a choke coil controls current with little power loss |
How to use / common traps: meters read RMS values, so an "AC mains of 220 V" is already an RMS figure. Example: R = 30 Ω, XL = 80 Ω, XC = 40 Ω on 200 V (rms) give Z = √(900 + 1600) = 50 Ω, Irms = 4 A, cos φ = 0.6 and P = 480 W, with the current lagging by about 53°. Using V0 in place of Vrms in P = VrmsIrms cos φ doubles the answer. In motional emf, v, l and B must be mutually perpendicular for ε = Blv; otherwise take the perpendicular components. For Lenz's law questions, state the direction and the reason (the change being opposed); the reason usually carries the mark.
Does your child know these formulas but still lose marks in the derivations and numericals? Book a free ISC Physics demo at home in Gurgaon or online. Our tutor will go through a recent test with you and show where the marks are going.
Book a Free ISC Physics Demo +91 92204 750885. Electromagnetic waves
This unit is worth 2 marks and the syllabus says "qualitative ideas only", so learn the facts and the order of the spectrum rather than derivations.
| Result | Formula or fact |
|---|---|
| Displacement current (basic idea) | Id = ε0 dΦE/dt; exists wherever the electric flux changes, for example between capacitor plates while charging |
| Transverse nature | E and B are perpendicular to each other and to the direction of travel |
| Speed and amplitudes (useful) | c = 1/√(μ0ε0) ≈ 3 × 108 m s−1; E0/B0 = c; c = fλ |
| Spectrum, increasing frequency (decreasing wavelength) | Radio and TV → microwaves → infrared → visible → ultraviolet → X-rays → gamma rays |
How to use / common traps: the syllabus asks for the source, detection and uses of each band, and "approximate range of λ or f or at least proper order". Learn one source and one use per band, and write the order both ways (by frequency and by wavelength), because questions flip it.
6. Optics
The syllabus lets you use any one sign convention for numericals. The table uses the Cartesian convention: distances measured from the pole or optical centre, positive in the direction of incident light.
Ray optics
| Result | Formula |
|---|---|
| Spherical mirror (derive) | 1/v + 1/u = 1/f; f = R/2; m = −v/u |
| Snell's law | n1 sin i = n2 sin r; n = c/v |
| Relative indices | 1n2 × 2n3 × 3n1 = 1 |
| Real and apparent depth | n = real depth/apparent depth (viewed normally) |
| Critical angle | sin C = 1/n (denser medium to air); TIR needs light going denser to rarer with i > C |
| Prism (derive) | A = r1 + r2; δ = i1 + i2 − A; at minimum deviation n = sin[(A + δm)/2]/sin(A/2) |
| Thin prism | δ = (n − 1)A |
| Dispersion | Angular dispersion δv − δr = (nv − nr)A; dispersive power ω = (nv − nr)/(ny − 1) |
| Single spherical surface (derive, one case) | n2/v − n1/u = (n2 − n1)/R |
| Lens maker's formula (derive) | 1/f = (n − 1)(1/R1 − 1/R2); in a liquid use (ng/nl − 1) |
| Thin lens (derive) | 1/v − 1/u = 1/f; m = v/u |
| Power and lenses in contact (derive) | P = 1/f (f in metres, unit dioptre); 1/F = 1/f1 + 1/f2; P = P1 + P2 |
Optical instruments
| Instrument | Magnifying power |
|---|---|
| Simple microscope (derive) | Image at D: M = 1 + D/f; image at infinity: M = D/f (D ≈ 25 cm) |
| Compound microscope | Image at D (derive): M = (vo/uo)(1 + D/fe) in magnitude; image at infinity (expression only): M = (vo/uo)(D/fe) |
| Refracting telescope (derive) | Image at infinity: M = fo/fe, tube length fo + fe; image at D: M = (fo/fe)(1 + fe/D) |
| Resolving power of a compound microscope (standard textbook form) | RP = 2n sin β/(1.22λ); larger for smaller λ and larger numerical aperture |
Wave optics
| Result | Formula |
|---|---|
| Huygens' principle and refraction | n = c/v = λair/λmedium; frequency does not change |
| Path and phase difference | Phase difference = (2π/λ) × path difference |
| Young's double slit, path difference | Δx = d sin θ ≈ yd/D (small θ) |
| Bright and dark fringes | Bright: Δx = nλ, yn = nDλ/d; dark: Δx = (n + ½)λ |
| Fringe width (derive) | β = Dλ/d |
| Single slit (width a), qualitative | Minima: a sin θ = nλ (n = 1, 2, 3, …); secondary maxima: a sin θ ≈ (n + ½)λ |
| Central maximum | Angular width 2λ/a; linear width 2Dλ/a |
How to use / common traps: pick one sign convention and never switch within a question. Example: a convex lens with f = +20 cm and an object at u = −30 cm gives 1/v = 1/20 − 1/30 = 1/60, so v = +60 cm and m = v/u = −2 (real, inverted, twice the size). In a liquid, the same lens can change a lot: with ng = 1.5 and nl = 1.25, the 20 cm lens becomes 20 × 0.5/0.2 = 50 cm. For a prism with A = 60° and δm = 30°, n = sin 45°/sin 30° = √2. In Young's experiment, d = 0.5 mm, D = 1 m and λ = 600 nm give β = 1.2 mm; convert all three to metres before dividing. The single-slit condition a sin θ = nλ gives minima, the opposite of the double-slit bright-fringe condition, and this swap is a favourite multiple-choice trap. For telescopes, the objective has the larger focal length.
From our tutors: Optics carries 18 of the 70 theory marks, the largest single unit, and most of the derivations in it start from a ray diagram. We see students lose marks on arrows missing from rays, the image drawn as solid when it is virtual, or no labels on f and 2f. Our routine is to practise the diagram on its own, timed, until it takes under two minutes, and only then practise the derivation that follows from it.
7. Dual nature of radiation and matter
| Result | Formula |
|---|---|
| Photon energy and momentum | E = hν = hc/λ; p = E/c = h/λ |
| Quick conversion (useful) | E (in eV) ≈ 1240/λ (in nm) |
| Einstein's photoelectric equation | Kmax = hν − W0; W0 = hν0 (threshold frequency ν0) |
| Stopping potential | eVs = Kmax; Vs = (h/e)ν − W0/e |
| Planck's constant from a graph | Slope of the Vs–ν graph = h/e; intercept on the ν-axis = ν0 |
| De Broglie wavelength | λ = h/p = h/mv = h/√(2mK) |
| Electron accelerated through V volts (derived) | λ = h/√(2meV) ≈ 1.227/√V nm |
How to use / common traps: intensity changes the number of photoelectrons (the saturation current), not their maximum kinetic energy; frequency changes the energy. Example: 400 nm light has E ≈ 1240/400 = 3.1 eV, so on a surface with W0 = 2.0 eV, Kmax ≈ 1.1 eV and Vs ≈ 1.1 V. Convert eV to joules (× 1.6 × 10−19) before using SI formulas. An electron accelerated through 100 V has λ ≈ 0.123 nm, which is why electrons diffract from crystals. The Davisson–Germer experiment is qualitative in the syllabus: learn the set-up and the conclusion, not a calculation.
8. Atoms and nuclei
| Result | Formula |
|---|---|
| Distance of closest approach (α particle, kinetic energy K) | K = (1/4πε0)(2e × Ze)/r0, so r0 = (1/4πε0)(2Ze2/K) |
| Bohr's quantum condition | mvr = nh/2π |
| Radius of the nth orbit (hydrogen) | rn = ε0n2h2/(πme2) ≈ 0.0529 n2 nm |
| Orbital speed | vn = e2/(2ε0nh) ≈ 2.2 × 106/n m s−1 |
| Energies (hydrogen) | En = −me4/(8ε02n2h2) = −13.6/n2 eV; KE = −En; PE = 2En |
| Emitted photon | hν = Ei − Ef |
| Rydberg formula | 1/λ = R(1/nf2 − 1/ni2), R ≈ 1.097 × 107 m−1 |
| Series (nf) | Lyman 1 (ultraviolet); Balmer 2 (visible); Paschen 3, Brackett 4, Pfund 5 (infrared) |
| Nuclear size and density | R = R0A1/3 (R0 ≈ 1.2 fm); density is about the same for all nuclei |
| Atomic mass unit | 1 u = 1/12 of the mass of a 12C atom = 1.66 × 10−27 kg ≈ 931.5 MeV/c2 |
| Mass defect and binding energy | Δm = [Zmp + (A − Z)mn] − Mnucleus; BE = Δm c2; E = mc2 |
| Energy from fission (syllabus example) | A = 240 nucleus at about 7.6 MeV per nucleon splits into two A = 120 nuclei at about 8.5 MeV per nucleon: Q = 240 × 0.9 ≈ 216 MeV, "about 200 MeV" |
| Fusion example | 4 1H → 4He (+ energy); needs temperatures of the order of 106 K or more |
How to use / common traps: the total energy of the electron is negative; "energy needed to ionise" is +13.6 eV from the ground state. Example: the Balmer line from n = 3 to n = 2 has 1/λ = R(1/4 − 1/9) = 5R/36, so λ ≈ 656 nm (red). Write it in nm, as the syllabus instructs. A 5 MeV α particle aimed at gold (Z = 79) gets no closer than about 45 fm, which is how Rutherford's experiment bounded the nuclear size. In binding energy questions, use atomic masses consistently and remember that BE per nucleon, not total BE, decides stability: the curve is highest for middle-mass nuclei, which is why both fission and fusion release energy.
9. Electronic devices
| Result | Formula or fact |
|---|---|
| Energy bands | Conductor: bands overlap; semiconductor: small gap (about 0.7 eV for Ge, 1.1 eV for Si); insulator: large gap (about 5–6 eV for diamond) |
| Carriers | Intrinsic: ne = nh; n-type (donor, group 15): electrons are majority carriers; p-type (acceptor, group 13): holes are majority carriers |
| p–n junction | Forward bias narrows the depletion region and current rises sharply after the knee voltage; reverse bias widens it, with a tiny current until breakdown |
| Rectifiers (output frequency) | Half-wave: same as input f; full-wave (two-diode, centre-tap): 2f |
| Zener regulator | Vout = VZ; IS = (Vin − VZ)/RS; IL = VZ/RL; IZ = IS − IL |
| LED, photodiode, solar cell | Photon energy relates to band gap: λ (nm) ≈ 1240/Eg (eV); LED forward biased, photodiode reverse biased, solar cell with no external bias |
How to use / common traps: the Zener diode is connected in reverse bias; drawing it forward biased loses the diagram marks. Example: Vin = 15 V, VZ = 6 V, RS = 500 Ω and RL = 2 kΩ give IS = 18 mA, IL = 3 mA and IZ = 15 mA. The syllabus asks for simple circuit diagrams and graphs of the half-wave and full-wave rectifier, and explicitly excludes the four-diode bridge rectifier. The band-gap values above are the commonly quoted approximate figures; the syllabus asks for energy gaps "in typical substances (carbon, Ge, Si)", so learn them to one decimal place.
Constants you should know by heart
The 2027 specimen paper prints a short list of useful constants at the end. It includes the electron mass (9.1 × 10−31 kg), the permittivity of vacuum (8.85 × 10−12 F m−1), 1 u (1.66 × 10−27 kg), 1 eV (1.6 × 10−19 J) and g (9.8 m s−2). The board paper may print a different list, so do not rely on it. Learn these as well:
| Constant | Value |
|---|---|
| Speed of light, c | 3 × 108 m s−1 |
| Planck's constant, h | 6.63 × 10−34 J s |
| Electronic charge, e | 1.6 × 10−19 C |
| 1/4πε0 | 9 × 109 N m2 C−2 |
| μ0 | 4π × 10−7 T m A−1 |
| Rydberg constant, R | 1.097 × 107 m−1 |
| 1 u in energy | 931.5 MeV |
| hc | about 1240 eV nm |
Formulas beyond the ISC 2027 Class 12 syllabus
Many formula sheets, and books written for JEE, NEET or other boards, include the items below. The official ISC 2027 Class XII Physics syllabus either does not name them or explicitly excludes them. If you are preparing for the ISC 2027 board paper, give them low priority, and check the current syllabus on cisce.org before relying on older material. If you are also preparing for JEE, keep them on your JEE sheet.
| Formula or topic | Unit it usually sits in | ISC 2027 Class XII syllabus |
|---|---|---|
| Field of a uniformly charged solid sphere; field of a toroid | Electrostatics; magnetism | Not named (Gauss: line, plane sheet and thin shell only; Ampere: wire and solenoid only) |
| Ampere's swimming rule | Magnetism | Explicitly not included; right-hand thumb rule only |
| Cyclotron and its frequency qB/2πm | Magnetism | Not named |
| Earth's magnetism: dip, declination, horizontal component | Magnetism | Not named |
| Magnetic field of a bar magnet derived | Magnetism | Formula only, "no derivations" |
| Energy stored in an inductor, ½LI2 | EMI | Not named in the text |
| Silvering of a lens | Ray optics | Explicitly excluded |
| Refraction through a prism or lens using Huygens' principle | Wave optics | Explicitly not required |
| Interference intensity I = I1 + I2 + 2√(I1I2) cos φ, derived from wave equations | Wave optics | Mathematical deduction "not required"; the intensity graph is asked |
| Polarisation: Malus's law, Brewster's law | Wave optics | Not named in Class XII |
| Rutherford's scattering formula | Atoms | Mathematical theory of scattering excluded |
| Radioactive decay law N = N0e−λt, half-life T½ = 0.693/λ, mean life, activity | Nuclei | Not named in the 2027 Class XII syllabus |
| Details of the chain reaction | Nuclei | "Not required"; reactor parts are qualitative only |
| Bridge rectifier with four diodes | Electronic devices | Explicitly not included |
| Transistor action, current gain β = ΔIC/ΔIB, amplifiers, logic gates | Electronic devices | Not in the theory syllabus; transistors appear only in the practical list (identifying components with a multimeter) |
"Not named" means the topic is absent from the syllabus text. It does not promise that no question will ever touch the idea, and CISCE can revise the syllabus. Our guide to ISC specimen papers 2027 explains how to use the specimen paper and older board papers without spending time on topics that have gone. If you are preparing for JEE alongside the board exam, our JEE Physics formula sheet covers the wider list.
Printing and daily revision
- Use your browser's Print option. The table of contents and booking boxes are hidden when you print, so the sheet prints as formulas and notes only.
- To keep a copy on your phone or laptop, choose "Save as PDF" as the printer. We do not offer a separate download.
- Revise for 10 to 15 minutes a day, two or three units in rotation, covering the formula column. Weight the rotation by marks: Optics (18) and the two magnetism and induction units (16 together) deserve more turns than Electromagnetic Waves (2).
- Pair every formula session with two numericals from the specimen paper or past papers, and write units in every line.
- Formulas are about half the story. The other half is the ray diagrams, derivations, graphs and the project; our guide on how to score 95+ in ISC Physics covers them, and ISC Physics project ideas covers the 10-mark project.
Doing Maths too? Our ISC Class 12 Maths formula sheet follows the same format for all seven Maths units.
Frequently asked questions
Does this ISC Class 12 Physics formula sheet cover the whole 2027 syllabus?
It covers the key formulas and relations for all nine units of the official ISC Year 2027 Physics (861) Class XII theory syllabus, in the same order. The theory paper also tests derivations, ray diagrams, graphs and explanations, so pair the sheet with the official specimen paper.
Can I download this as a PDF?
We do not offer a separate download. The page is built to print: use your browser's Print option and choose "Save as PDF" if you want a copy on your device.
Which unit carries the most marks in ISC Class 12 Physics?
Optics, with 18 of the 70 theory marks. Magnetic Effects of Current and Magnetism plus Electromagnetic Induction and Alternating Currents carry 16 marks together, and Electrostatics plus Current Electricity carry 14 together. Electromagnetic Waves carries only 2.
Is a calculator allowed in the ISC Physics exam?
The official 2027 specimen paper says a simple scientific calculator without a programmable memory may be used. Check the instructions on your actual board paper, as they are the final word.
Is radioactivity in the ISC Class 12 Physics syllabus for 2027?
The 2027 Class XII syllabus lists composition and size of the nucleus, mass defect, binding energy, and fission and fusion under Nuclei. It does not name radioactive decay, half-life or activity, so we have placed them in the flagged table above.
Which sign convention should I use in optics numericals?
The syllabus says any one sign convention may be used. Most students use the Cartesian convention shown here. What matters is using one convention consistently throughout a question.
Are transistors and logic gates in ISC Class 12 Physics?
Not in the 2027 theory syllabus, which covers energy bands, semiconductors, the p–n junction diode, rectifiers, the LED, photodiode, solar cell and Zener diode. Transistors appear only in the practical list, where students identify components and use a multimeter.
How should my child revise Physics formulas each day?
Ten to fifteen minutes a day, covering the formula column and writing from memory, then two numericals on anything missed. A home tutor can make this routine stick and check the working and units, not just the final answer.
Want a tutor to turn this ISC Class 12 Physics formula sheet into marks? Book a free ISC Physics demo with Ajay Vatsyayan Classes, Saraswati kunj II, Wazirabad, Sector 52, Gurugram, Haryana 122003. Male and female tutors are available, at home across Gurgaon or online. You can also see our Class 12 tuition in Gurgaon options.
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