JEE Physics — Complete Preparation Guide
Physics is the most conceptual subject in JEE. Students who understand the physics score well; students who memorise formulas struggle. This guide covers every chapter with the right depth, common traps, and problem-solving frameworks.
Exam Weightage
Topic JEE Main JEE Advanced
Mechanics (total) ~35% ~32%
Kinematics 5% 4%
Newton's Laws + Friction 7% 6%
Work Energy Power 5% 5%
Rotation 8% 8%
Gravitation 5% 4%
Fluid Mechanics 5% 5%
Electromagnetism (total) ~30% ~30%
Electrostatics 8% 8%
Current Electricity 7% 6%
Magnetism + EMI 10% 10%
AC Circuits 5% 6%
Modern Physics ~12% ~12%
Waves + Optics ~15% ~16%
Thermodynamics ~8% ~10%Mechanics
Kinematics
Equations of motion (uniform acceleration):
v = u + at
s = ut + ½at²
v² = u² + 2as
s_nth = u + a(2n-1)/2
Projectile motion:
Horizontal: x = u cosθ · t (constant velocity)
Vertical: y = u sinθ · t - ½gt² (accelerated)
Time of flight: T = 2u sinθ/g
Max height: H = u²sin²θ/2g
Range: R = u²sin2θ/g
Max range at θ = 45°: R_max = u²/g
Complementary angles give same range:
θ and (90°-θ) have equal horizontal range
Relative velocity:
v_AB = v_A - v_B (velocity of A with respect to B)
River boat: Boat at angle θ upstream to cross perpendicular
θ = sin⁻¹(v_river/v_boat)
Time = width / v_boat cosθNewton's Laws
Key concepts GATE and JEE Advanced target:
Pseudo force: In accelerating frame, F_pseudo = -ma (in direction opposite to acceleration)
Elevator problems: N = m(g ± a) [+ going up, - going down]
Normal force ≠ mg in general
Normal force = component of net force perpendicular to surface
Friction:
Static: f_s ≤ μ_s N (static friction adjusts up to maximum)
Kinetic: f_k = μ_k N (constant once sliding begins)
μ_k < μ_s always
Friction provides centripetal force on circular curves
Max speed on banked road: v = √(rg · tan θ) without friction
Spring problems:
F = kx, PE = ½kx²
Springs in series: 1/k_eq = 1/k₁ + 1/k₂ (weaker spring)
Springs in parallel: k_eq = k₁ + k₂ (stiffer)Rotation — JEE's Hardest Mechanics Topic
Moment of inertia:
Point mass: I = mr²
Solid cylinder: I = ½mr²
Hollow cylinder: I = mr²
Solid sphere: I = 2mr²/5
Hollow sphere: I = 2mr²/3
Rod about centre: I = mL²/12
Rod about end: I = mL²/3
Parallel axis theorem: I = I_cm + md²
Perpendicular axis theorem: I_z = I_x + I_y (only for laminas/flat objects)
Torque and angular acceleration:
τ = Iα (analogous to F = ma)
τ = r × F
Rolling without slipping:
v_cm = ωR (constraint equation)
Total KE = ½mv² + ½Iω² = ½mv²(1 + I/mR²)
For solid sphere: KE = ½mv²(1 + 2/5) = 7mv²/10
Acceleration on incline: a = g sinθ/(1 + I/mR²)
Solid sphere rolls fastest down incline (lowest I/mR²)Electrostatics
Coulomb's law: F = kq₁q₂/r² k = 9×10⁹ N·m²/C²
Electric field:
Point charge: E = kq/r²
Infinite wire: E = λ/2πε₀r
Infinite plane: E = σ/2ε₀ (independent of distance!)
Inside conductor: E = 0
Gauss's law: ∮E·dA = Q_enc/ε₀
Most powerful tool for symmetric charge distributions
Electric potential:
V = kq/r (point charge)
V is scalar, E is vector: E = -dV/dr
Work done = q(V_A - V_B)
Capacitors:
C = Q/V = ε₀A/d (parallel plate)
Series: 1/C_eq = 1/C₁ + 1/C₂
Parallel: C_eq = C₁ + C₂
Energy stored: U = ½CV² = Q²/2C
Dielectric: C = κC₀ (κ = dielectric constant)
Conductor in field: Charges redistribute until E=0 inside
Cavity inside conductor: E=0 (shielding)
Field just outside conductor: E = σ/ε₀Current Electricity
Ohm's law: V = IR, R = ρL/A
Kirchhoff's Laws (KCL and KVL):
KCL: ΣI_in = ΣI_out at any junction
KVL: ΣV = 0 around any closed loop
Loop sign convention:
Go through battery from - to +: add EMF
Go through resistor in direction of current: subtract IR
Wheatstone bridge balanced: P/Q = R/S → no current through galvanometer
Potentiometer:
Measures EMF without drawing current (high accuracy)
Works on null deflection principle
Colour code for resistors:
Black Brown Red Orange Yellow Green Blue Violet Grey White
0 1 2 3 4 5 6 7 8 9
Tolerance: Gold ±5%, Silver ±10%
Power: P = IV = I²R = V²/R
Cells in series: EMF adds, internal resistance adds
Cells in parallel: EMF same, internal resistance reducesModern Physics — High Scoring, Conceptual
Photoelectric effect:
KE_max = hf - φ (φ = work function)
Threshold frequency: f₀ = φ/h
Stopping potential: eV₀ = KE_max
Einstein's insight: Light behaves as particles (photons)
Energy of photon: E = hf = hc/λ
h = 6.63×10⁻³⁴ J·s
de Broglie wavelength:
λ = h/p = h/mv
Bohr's model of hydrogen:
Radius: r_n = 0.53n² Å
Energy: E_n = -13.6/n² eV
Speed: v_n = 2.18×10⁶/n m/s
Spectral series:
Lyman: n→1 (UV)
Balmer: n→2 (visible)
Paschen: n→3 (IR)
Radioactivity:
N = N₀e^(-λt)
Half-life: T₁/₂ = ln2/λ = 0.693/λ
Activity: A = λN
α decay: Z-2, A-4
β⁻ decay: Z+1, A same
γ decay: Z same, A same (energy release only)
Nuclear binding energy:
BE = Δm × c² (Δm = mass defect)
Fission: Heavy nucleus splits (U-235, Pu-239) → energy released
Fusion: Light nuclei combine (H isotopes) → more energy per unit massOptics
Ray optics:
Mirror formula: 1/v + 1/u = 1/f
Lens formula: 1/v - 1/u = 1/f
Magnification: m = -v/u (mirror), +v/u (lens)
Sign convention: Object on left, distances right = positive
Power of lens: P = 1/f(metres), unit = Dioptre
Lenses in contact: P_eq = P₁ + P₂
Snell's law: n₁ sinθ₁ = n₂ sinθ₂
Critical angle: sin C = 1/n (for total internal reflection)
Wave optics — Young's double slit:
Path difference: Δ = d sinθ ≈ yd/D
Bright fringes: Δ = nλ
Dark fringes: Δ = (2n-1)λ/2
Fringe width: β = λD/d
Increasing D: Fringe width increases
Increasing d: Fringe width decreases
Submerge in water: λ_water = λ_air/n → fringe width decreasesPrevious Year Pattern — What Advanced Tests
JEE Advanced Physics characteristics:
Conceptual reasoning over formula plugging
Multiple correct options — partial marking for wrong option
Integer answer type — no negative marking
Common Advanced-only topics:
- Electromagnetic induction with moving circuits
- Rotation with friction (complex constraint problems)
- Interference with thin films
- Non-uniform electric fields
- RC/RL transient circuits
Strategy:
Main: 3 full topics mastered > 8 half-mastered
Advanced: Focus on Mechanics + Electromagnetism (60% weightage)
Must solve: HC Verma (conceptual foundation) + DC Pandey (variety)
Past papers: 2005-2024 JEE Advanced mandatory
