NEET physics formula sheet, with the conditions that matter

In this guide

How to use this sheet
Units, measurement and kinematics
Laws of motion, work, energy and power
Rotational motion
Gravitation
Solids, fluids and heat
Thermodynamics and kinetic theory
Oscillations and waves
Electrostatics and current electricity
Magnetism, EMI and AC
Optics
Modern physics and semiconductors
Quick self-test
What to do next

A formula sheet is only useful if it tells you when each formula works. Most wrong answers in NEET physics come from a correct formula used in the wrong situation: an equation of motion with changing acceleration, the small-height gravity approximation at a large height, or a series rule applied to capacitors in parallel.

So this sheet lists each formula with its condition or its trap. Read it once a week in the last three months, and daily in the last fortnight. It is a revision tool, not a first reading: if a line here makes no sense, go back to that chapter's guide.

How to use this sheet

Cover the right-hand column and say the condition aloud before you check it.
Mark the lines you hesitate on, and copy only those to a short personal sheet.
Pair each line with one question. A formula you have used in a numerical this week is a formula you will remember in the hall.

Units, measurement and kinematics

Formula	Condition or trap
Z = AᵖBᵠ/Cʳ gives ΔZ/Z = pΔA/A + qΔB/B + rΔC/C	Relative errors always add, even when quantities divide
Z = A ± B gives ΔZ = ΔA + ΔB	Absolute errors add, even for a difference
v = u + at, s = ut + ½at², v² = u² + 2as	Constant acceleration only
Distance in the nth second: sₙ = u + a(2n − 1)/2	Constant acceleration
Projectile: T = 2u sin θ/g, H = u² sin²θ/2g, R = u² sin 2θ/g	Level ground, no air resistance; R is greatest at 45°
Uniform circular motion: a = v²/r = ω²r	Directed towards the centre

Laws of motion, work, energy and power

Formula	Condition or trap
F = dp/dt; impulse = FΔt = Δp	Use Δp for collisions and catches
Static friction f ≤ μₛN; kinetic f = μₖN	Static friction adjusts up to its maximum
Apparent weight in a lift: m(g + a) when accelerating up, m(g − a) when accelerating down	Free fall: apparent weight is zero
Safe speed on a flat curve: v = √(μrg)	Friction supplies the centripetal force
Banked road without friction: tan θ = v²/rg	The speed at which no friction is needed
W = Fs cos θ; W_net = ΔK	Work–energy theorem holds for all forces together
Spring energy ½kx²; P = Fv	x is measured from the natural length
Vertical circle: v at top ≥ √(gr); v at bottom ≥ √(5gr)	For a string, to complete the circle
Perfectly inelastic: v = (m₁u₁ + m₂u₂)/(m₁ + m₂)	KE is lost; momentum is conserved
Elastic, equal masses, one at rest	Velocities are exchanged

Rotational motion

Formula	Condition or trap
τ = r × F; τ = Iα; L = Iω	I depends on the axis
Ring MR²; disc ½MR²; solid sphere ⅖MR²; hollow sphere ⅔MR²; rod (centre) ML²/12	About the symmetry axis or diameter as usual
Parallel axes: I = I_cm + Md²	One axis must pass through the centre of mass
Perpendicular axes: I_z = I_x + I_y	Plane (flat) bodies only
I₁ω₁ = I₂ω₂	No external torque
Rotational KE = ½Iω²	Add ½Mv² of the centre of mass if it also translates

Gravitation

Formula	Condition or trap
g = GM/R²	At the surface
g(h) = gR²/(R + h)² ≈ g(1 − 2h/R)	The approximation needs h ≪ R
g(d) = g(1 − d/R)	Uniform Earth; g = 0 at the centre
U = −GMm/r	Zero at infinity
Orbital speed v = √(GM/r) ≈ √(gR) near the surface	About 7.9 km/s close to Earth
Escape speed v_e = √(2GM/R) = √(2gR)	About 11.2 km/s; independent of the mass launched
T² ∝ r³ (T = 2π√(r³/GM))	Kepler's third law
Total energy of a satellite = −GMm/2r	KE = +GMm/2r

Solids, fluids and heat

Formula	Condition or trap
Y = (F/A)/(ΔL/L)	Within the elastic limit
P = P₀ + ρgh	Fluid at rest
A₁v₁ = A₂v₂; P + ½ρv² + ρgh = constant	Incompressible, non-viscous, steady flow along a streamline
Torricelli: v = √(2gh)	Speed of efflux from depth h
Stokes: F = 6πηrv; terminal speed v = 2r²(ρ − σ)g/9η	Small sphere, slow flow
Excess pressure: drop 2T/r, soap bubble 4T/r	A bubble has two surfaces
Capillary rise h = 2T cos θ/rρg	Falls (h < 0) when θ > 90°, as with mercury
ΔL = LαΔT; β = 2α; γ = 3α	Isotropic solids
Q = mcΔT; Q = mL	No temperature change during a change of state
Conduction H = kAΔT/L; radiation H = eσAT⁴	T in kelvin for radiation
Wien: λ_m T = constant; Newton's cooling: rate ∝ (T − Tₛ)	Newton's law for small temperature differences

Thermodynamics and kinetic theory

Formula	Condition or trap
ΔQ = ΔU + ΔW	ΔW is work done by the gas (physics convention)
Isobaric W = PΔV; isochoric W = 0	Work is the area under the P–V curve
Isothermal W = nRT ln(V₂/V₁); ΔU = 0	Ideal gas
Adiabatic PVᵞ = constant; W = nR(T₁ − T₂)/(γ − 1)	Q = 0
Cp − Cv = R; γ = 5/3 (monatomic), 7/5 (diatomic)	Per mole, ideal gas
Carnot efficiency η = 1 − T₂/T₁	T in kelvin; the upper limit for any engine between T₁ and T₂
v_rms = √(3RT/M)	M in kg mol⁻¹
Mean KE per molecule = (3/2)kT	Translational only
Equipartition: ½kT per degree of freedom	Diatomic gas at room temperature: 5 degrees

Oscillations and waves

Formula	Condition or trap
x = A sin(ωt + φ); v = ω√(A² − x²); a = −ω²x	SHM only
Total energy ½kA² = ½mω²A²	Constant; KE and PE trade places
Spring T = 2π√(m/k); pendulum T = 2π√(l/g)	Pendulum: small angles
v = fλ; string v = √(T/μ)	μ is mass per unit length
Speed of sound v = √(γP/ρ)	Laplace's correction
String fixed at both ends or open pipe: fₙ = nv/2L	All harmonics
Closed pipe: f = (2n − 1)v/4L	Odd harmonics only
Beats = f₁ − f₂	Small frequency difference

Electrostatics and current electricity

Formula	Condition or trap
F = kq₁q₂/r², k = 9 × 10⁹ N m² C⁻²	Point charges
Dipole field: axial 2kp/r³, equatorial kp/r³	r much larger than the dipole length
Torque on a dipole τ = pE sin θ	Net force is zero in a uniform field
Gauss: flux = q_enclosed/ε₀	Only enclosed charge counts
Line charge λ/2πε₀r; sheet σ/2ε₀	Infinite line or sheet
C = ε₀A/d; with dielectric KC	Parallel plates
U = ½CV² = Q²/2C	Series: 1/C = ∑1/Cᵢ; parallel: C = ∑Cᵢ
I = neAv_d; R = ρl/A	Stretching a wire keeps its volume fixed
V = E − Ir (discharging); V = E + Ir (charging)	Internal resistance r
Wheatstone balance: P/Q = R/S	No current through the galvanometer
P = VI = I²R = V²/R	Use I²R for series, V²/R for parallel comparisons

Magnetism, EMI and AC

Formula	Condition or trap
Long straight wire B = μ₀I/2πr; loop centre μ₀I/2R; solenoid μ₀nI	Solenoid: long, field inside
F = qvB sin θ; r = mv/qB; T = 2πm/qB	T does not depend on speed
Force on a wire F = BIl sin θ; between wires μ₀I₁I₂/2πd per metre	Like currents attract
Torque on a coil τ = NIAB sin θ	θ is between the field and the coil's normal
Ammeter shunt S = I_g G/(I − I_g); voltmeter series R = V/I_g − G	Shunt is small and in parallel; the voltmeter resistor is large and in series
e = −dΦ/dt; motional e = Blv	Lenz's law gives the minus sign
Inductor energy ½LI²	Stored in the magnetic field
V_rms = V₀/√2; X_L = ωL; X_C = 1/ωC	Sinusoidal AC; X_C falls as frequency rises
Z = √[R² + (X_L − X_C)²]; resonance ω₀ = 1/√(LC)	At resonance Z = R, current is greatest
P = V_rms I_rms cos φ; cos φ = R/Z	Pure L or C: power is zero
Transformer V_s/V_p = N_s/N_p = I_p/I_s	Ideal transformer
EM waves: c = 1/√(μ₀ε₀); E₀ = cB₀	E and B are in phase and perpendicular

Optics

Formula	Condition or trap
Mirror 1/v + 1/u = 1/f; f = R/2; m = −v/u	Cartesian signs
Lens 1/v − 1/u = 1/f; m = v/u	Concave lens f is negative
Lens maker: 1/f = (n − 1)(1/R₁ − 1/R₂)	Thin lens; n relative to the surroundings
P = 1/f (f in metres); P = P₁ + P₂	Thin lenses in contact
Critical angle sin C = 1/n	Light going from denser to rarer
Prism n = sin[(A + D_m)/2]/sin(A/2); thin prism δ = (n − 1)A	Minimum deviation: the ray passes symmetrically
Apparent depth = real depth/n	Viewed from above, near normal
YDSE fringe width β = λD/d	In a medium, λ becomes λ/n
Single slit minima a sin θ = nλ; central maximum 2λD/a wide	Here the condition gives dark bands, not bright
Malus I = I₀ cos²θ; Brewster tan θ_B = n	Unpolarised light through one polaroid: I₀/2

Modern physics and semiconductors

Formula	Condition or trap
K_max = hν − φ₀ = eV₀	Intensity changes current, not K_max
E (eV) ≈ 1240/λ (nm)	Photon energy
λ = h/p = h/√(2mK); electron λ ≈ 1.227/√V nm	V in volts
Eₙ = −13.6 Z²/n² eV; rₙ ∝ n²/Z	Hydrogen-like atoms
Lines from level n: n(n − 1)/2	Many atoms, all transitions
R = R₀A¹ᐟ³ (cube root of A), R₀ ≈ 1.2 fm	Nuclear density is the same for all nuclei
BE = Δm × 931.5 MeV (Δm in u)	BE per nucleon peaks near A = 56
ne × nh = nᵢ²	Thermal equilibrium
Full-wave output frequency = 2 × input	Half-wave: same as input

Quick self-test

The percentage error in the radius of a sphere is 2%. The percentage error in its volume is: (a) 2% (b) 4% (c) 6% (d) 8%
A satellite's orbital radius is doubled. Its orbital speed becomes: (a) 2 times (b) √2 times (c) 1/√2 times (d) ½
A closed pipe 50 cm long, with sound at 340 m/s, has a fundamental frequency of: (a) 170 Hz (b) 340 Hz (c) 680 Hz (d) 85 Hz
At resonance in a series LCR circuit, the impedance equals: (a) X_L (b) X_C (c) R (d) zero
Two thin lenses of power +5 D and −3 D are in contact. The combined focal length is: (a) 50 cm (b) 20 cm (c) 12.5 cm (d) 2 m
A Carnot engine works between 500 K and 300 K. Its efficiency is: (a) 20% (b) 40% (c) 60% (d) 67%
In YDSE, the whole set-up is dipped in water (n = 4/3). The fringe width: (a) becomes 4/3 times (b) becomes 3/4 times (c) is unchanged (d) becomes zero
The rms voltage of a 311 V peak AC supply is about: (a) 155 V (b) 220 V (c) 311 V (d) 440 V

Answers

(c) V ∝ r³, so 3 × 2% = 6%.
(c) v ∝ 1/√r.
(a) f = v/4L = 340/(4 × 0.5) = 170 Hz.
(c) X_L = X_C, so Z = R.
(a) P = +2 D, f = 1/2 m = 50 cm.
(b) 1 − 300/500 = 0.4.
(b) λ becomes λ/n, so β becomes 3β/4.
(b) 311/√2 ≈ 220 V.

What to do next

Cover the right-hand column of one table a day and recite the conditions.
Copy every line you missed onto one personal page. That page is your last-week sheet.
Pair this sheet with solving physics numericals faster and common physics mistakes, then move to chemistry with the NEET chemistry plan.

A note on dates and numbers. Exam patterns, vacancies and schedules change from year to year. Always confirm the current details in the latest notification on the National Testing Agency website .

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