Complete Class 12th PHYSICS in 1 Shot JEE 2026

Complete Class 12th Physics in 1 Shot for JEE 2026:  Preparing for JEE 2026 can be challenging, but it’s possible to cover the entire Class 12 Physics syllabus in one go with the right strategy. By focusing on key concepts, important formulas, and high-weight topics, you can revise efficiently and strengthen your problem-solving skills. 

Combining theory with the regular practice of previous years’ questions and mock tests will help you build speed and accuracy. This approach ensures that even if you’re short on time, you can confidently complete the Class 12 Physics syllabus and stay well-prepared for JEE 2026.

Complete Class 12th Physics in 1 Shot

This comprehensive review focuses on high-scoring concepts for JEE Mains. The approach directly connects theoretical foundations to problem-solving strategies, enabling the effective application of formulas and concepts. Success hinges on correctly identifying the relevant concept and applying the appropriate formula without overcomplicating problems.

Also Check: JEE Mains 2026 Deleted Syllabus

Chapter: Electromagnetic (EM) Waves

This topic offers high-scoring potential for minimal effort, often yielding at least one question per paper.

1. Fundamental Concepts of EM Waves

Electromagnetic waves consist of electric (E) and magnetic (B) fields oscillating perpendicularly to each other and to the direction of wave propagation (v).

Key Relationships:

1. Magnitude: E = vB. In vacuum, E = cB. CAUTION: Always verify wave velocity v from its equation; do not assume c unless specified.

2. Vector: Directions of E, B, and v are mutually perpendicular, following a right-hand rule.

• [Memory Tip] Use the (EBC cyclic diagram). For instance, v̂ = Ê x B̂.

2. Analyzing the Wave Equation: A Core Skill

This is the most probable question type, typically involving finding the B-field from an E-field equation (or vice-versa).

Example Equation: E = E₀ sin(ωt - kx + φ)

Key Principles:

1. Phase: Identical for both electric and magnetic fields.

2. Direction of Propagation (v̂): Determined by the sign between ωt and kx. ωt - kx means positive x-direction (+î); ωt + kx means negative x-direction (-î).

3. Wave Speed (v): Critical step. Calculate using v = ω/k. This may not always be c.

3. Speed, Permittivity, and Permeability

Wave speed is tied to the medium's properties:

• In vacuum: c = 1 / √(μ₀ε₀)

• In a medium: v = 1 / √(με)

• Refractive index n = c/v = √(μᵣεᵣ).

Worked Examples: EM Waves

Example: Calculating Wave Velocity

Given E = 50 sin(500x - 10x10¹⁰t).

ω = 10 x 10¹⁰, k = 500.

v = ω/k = (10 x 10¹⁰) / 500 = 2 x 10⁸ m/s.

Example: The Velocity Trap Question

Given B_y = 5x10⁻⁶ sin(5x - 4x10⁸t). Find the amplitude of the electric field.

1. v = ω/k = (4 x 10⁸) / 5 = 0.8 x 10⁸ m/s.

2. Since v ≠ c, use E₀ = vB₀.
   E₀ = (0.8 x 10⁸) * (5 x 10⁻⁶) = 400 V/m.

Energy in Electromagnetic Waves

Energy density is energy per unit volume. Energy is equally shared between electric and magnetic fields.

Total average energy density: u_avg = (1/2)ε₀E₀² or B₀² / (2μ₀).

Total Energy (U) within volume V: U = u_avg × V.

Intensity of Electromagnetic Waves

Intensity (I) is power transmitted per unit area.

I = Power / Area

Relationship with E-field amplitude: I = u_avg × c = (1/2)ε₀cE₀².

Displacement Current

In a charging/discharging capacitor, conduction current (I_C) in wires equals displacement current (I_D) between plates.

I_D = I_C

I = dQ/dt = C (dV/dt).

Displacement current density J_D = I_D / A.

Wave Optics: Interference

Interference results from superposition of coherent waves, leading to energy redistribution.

Comparative Structure: Conditions for Interference

Wave Optics: Young's Double Slit Experiment (YDSE)

YDSE demonstrates interference. D = screen distance, d = slit separation, λ = wavelength.

Relation between Slit Width, Amplitude, and Intensity

If Amplitude (A) ∝ slit width (w), then Intensity (I) ∝ w². This modifies I_max/I_min calculations.

Example: If I_max / I_min = 9/4 and A ∝ w, for slit widths d and xd.

((x+1)/(x-1))² = 9/4 => (x+1)/(x-1) = 3/2 => x = 5.

YDSE with Polychromatic Light

Each wavelength λ produces its own fringe pattern with β = λD/d.

• Central Maxima (CM): Coincides for all colors.

• Coincidence of Maxima: n₁λ₁ = n₂λ₂.

Example: Where do bright fringes of λ₁ = 300 nm and λ₂ = 400 nm first coincide?

n₁ * 300 = n₂ * 400 => 3n₁ = 4n₂. Smallest integers: n₁ = 4, n₂ = 3.

So, 4th maximum of 300 nm coincides with 3rd maximum of 400 nm.

YDSE in a Medium

If the apparatus is in a medium of refractive index n:

• Wavelength changes: λ_medium = λ_air / n.

• Fringe width changes: β_medium = β_air / n (decreases).

• Central maxima position does not change.

YDSE with a Glass Slab

Placing a slab (thickness t, refractive index μ) in front of one slit:

• Fringe width (β) does not change.

• The entire pattern shifts. Shift distance: y₀ = (μ - 1)t * (D/d). Direction is towards the slab.

Thin-Film Interference

Conditions for interference depend on an optical path difference (2μt) and phase shift upon reflection.

• [Memory Tip] Reflection from a denser medium causes a (π phase shift). Reflection from a rarer medium causes (no phase shift).

• Net 0 or 2π shift: Maxima for 2μt = nλ, Minima for 2μt = (2n - 1)λ/2.

• Net π shift: Maxima for 2μt = (2n - 1)λ/2, Minima for 2μt = nλ.

Polarization using Polaroids (Malus's Law)

This is a very important topic.

1. Unpolarized Light through First Polarizer: Transmitted intensity is I₁ = I₀ / 2.

2. Polarized Light through Analyzer (Malus's Law): I_out = I_in * cos²θ (θ is angle between polarization and analyzer axis).

Example: Three polaroids P1, P2, P3. P2 at 60° to P1, P3 at 90° to P1. I₀ = 256 W/m².

1. After P1: I₁ = 256 / 2 = 128.

2. After P2: I₂ = 128 * cos²(60°) = 32.

3. After P3: Angle between P2 axis (60°) and P3 axis (90°) is 30°. I₃ = 32 * cos²(30°) = 32 * (3/4) = 24 W/m².

Polarization by Reflection: Brewster's Angle

At Brewster's Angle (θ_B), reflected light is fully polarized.

• Formula: tan(θ_B) = n2 / n1.

• Key Property: At θ_B, the reflected ray and refracted ray are perpendicular (90°).

• Refractive index n = √(μᵣεᵣ). Assume μᵣ = 1 for dielectrics.

Diffraction (Single-Slit)

• Minima (Dark Fringes): a * sin(θ) = nλ. Linear position y_min = nλD / a.

• Secondary Maxima (Bright Fringes): a * sin(θ) = (2n + 1)λ / 2. Linear position y_max ≈ (2n + 1)λD / 2a.

• Central Maxima Width: Linear width = 2λD / a. Secondary maxima are half this width.

Ray Optics: Plane Mirrors

• Image is virtual, erect, same size, same distance behind as object in front.

• Combination of Two Plane Mirrors:

• Parallel Mirrors: Infinite images.

• Inclined Mirrors (angle θ): Number of images N = (360/θ) - 1 if 360/θ is even OR if 360/θ is odd and object is on angle bisector. N = 360/θ if 360/θ is odd and object is asymmetrical. JEE Tip: Assume asymmetrical unless stated otherwise for odd m = 360/θ.

Refraction and Total Internal Reflection (TIR)

• Snell's Law: sin(i) / sin(r) = n2 / n1 = v1 / v2 = λ1 / λ2. Frequency (f) is constant.

• TIR Conditions: 1) Denser to rarer medium. 2) i > C.

• Critical Angle (C): sin(C) = n_rarer / n_denser. (Smaller n / Larger n).

Circle of Illuminance

Light from a source at depth H in denser medium emerges through a circular area of radius R = H tan(C).

Prism

Prisms bend light towards their base.

• Angle of Deviation (δ): δ = I + E - A.

• Prism Angle (A): A = R₁ + R₂.

• Minimum Deviation (δ_min): Occurs when I = E and R₁ = R₂ = A/2. Formula: δ_min = 2I - A. Light ray is parallel to the base.

• Small Angle Prism: δ = (n - 1)A.

• Dispersion: θ = (n_v - n_r)A. Dispersive power ω = (n_v - n_r) / (n_y - 1).

• Combination of Prisms: Achromatic (no dispersion) θ_net = 0. Direct Vision (no deviation) δ_net = 0.

Apparent Depth

When viewed from a rarer medium:

• Apparent Depth = Real Depth / n.

• For multiple layers: Total Apparent Depth = (t₁/n₁) + (t₂/n₂) + ....

Glass Slab and Lateral Shift

A parallel-sided slab causes zero net deviation but a lateral shift d = t * sin(I - R) / cos(R).

Spherical Mirrors

• Mirror Formula: 1/v + 1/u = 1/f.

• Focal Length: f = R/2. Concave f is negative, Convex f is positive.

• Magnification: m = -v/u = hᵢ / h₀.

• Longitudinal Velocity of Image: Vᵢ = - (v²/u²) * V₀.

Refraction at a Single Spherical Surface

nᵣ/v - nᵢ/u = (nᵣ - nᵢ)/R.

• nᵢ: refractive index of incident medium.

• nᵣ: refractive index of refracted medium.

• Sign Convention: Incident light direction is negative.

Focal Length of a Lens (Lens Maker's Formula)

• In Air: 1/f = (n - 1) (1/R₁ + 1/R₂)

• [Memory Tip] (For this specific formula, use: convex surface R is positive, concave R is negative.)

• In Medium: 1/f_medium = ((n_lens/n_surrounding) - 1) (1/R₁ + 1/R₂)

• Ratio: f_air / f_medium = ((n_lens/n_surrounding) - 1) / (n_lens - 1).

• Cutting Lenses:

• Along principal axis (horizontal): P and f unchanged.

• Perpendicular to principal axis (vertical): P becomes P/2, f becomes 2f.

• Combination of Lenses: P_eq = P₁ + P₂, 1/f_eq = 1/f₁ + 1/f₂.

• Silvering of a Lens: The system acts as an equivalent mirror. 1/F_eq = 1/f_m - 2/f_l. (Often f_m = R/2).

The Lens Formula

• Position: 1/v - 1/u = 1/f.

• Transverse Magnification: m = v/u.

• Velocity of Image (Longitudinal): v_image = (v/u)² * v_object.

Human Eye and Vision Defects

Optical Instruments

Simple Microscope

• Image at Infinity: M = D / f.

• Image at Near Point: M = 1 + (D / f).

Compound Microscope

• Approximate Magnification: M = (L / F_o) * (D / F_e) (for JEE Mains, L = tube length, D = 25 cm).

Astronomical Telescope (Normal Adjustment)

• Angular Magnification: M = F_o / F_e.

• Tube Length: L = F_o + F_e.

Force and Potential Energy Between Two Point Charges

• Electrostatic Force: F = k * q1 * q2 / r² (Vector).

• Potential Energy: U = k * q1 * q2 / r (Scalar - include sign of charges).

• Superposition Principle: Net force/potential is vector/scalar sum.

• Effect of Dielectric (K): F_medium = F_vacuum / K.

Electric Field (E) and Potential (V) of Various Geometries

• Point Charge: E = kQ / R², V = kQ / R.

• Uniformly Charged Arc (center): E = (2kλ / r) * sin(θ/2). V = kQ_total / r.

• Uniformly Charged Ring (on axis x): E = kQx / (R² + x²)^(3/2) (max at x = ±R/√2). V = kQ / √(R² + x²).

• Uniformly Charged Disk (on axis x): E = σ/(2ε₀) * [1 - x/√(R² + x²)]. V = σ/(2ε₀) * [√(R² + x²) - x].

• Infinite Sheet: E = σ / (2ε₀) (uniform).

• Between Oppositely Charged Parallel Plates: E = σ/ε₀.

• Infinite Long Wire: E = 2kλ / R.

• Hollow Sphere (R, Q): E_in = 0, V_in = kQ/R. E_out = kQ/r², V_out = kQ/r.

• Solid Sphere (R, Q): E_out = kQ/r², V_out = kQ/r. E_in = kQr / R³, V_in = (kQ / 2R³) * (3R² - r²).

• Solid Sphere with Off-Center Cavity: E_cavity = ρa / (3ε₀) (uniform, a = vector from sphere center to cavity center).

Relationship Between Electric Field and Potential

dV = -E · dr or E = -∇V.

The Electric Dipole

• Dipole Moment (p): p = qd (from -q to +q).

• Electric Field: E_axial = 2kp / r³, E_equatorial = kp / r³. E_axial is twice E_equatorial.

• In Uniform Field E:

• Torque: τ = pE sinθ (τ = p × E).

• Potential Energy: U = -pE cosθ (U = -p · E).

• Work Done (0° to 180°): W = 2pE.

• Time Period of Small Oscillation: T = 2π√(I / pE).

Electric Flux and Gauss's Law

• Electric Flux (Φ): Φ = E ⋅ A = EA cos(θ).

• Gauss's Law: Φ_net = ∮ E ⋅ dA = Q_enclosed / ε₀.

• Applications for Symmetry:

• Charge q at center of cube: Φ_total = q / ε₀, Φ_face = q / (6ε₀).

• Charge q at face center: Φ = q / (2ε₀).

• Charge q at edge center: Φ = q / (4ε₀).

• Charge q at corner: Φ = q / (8ε₀).

Fundamental Relations in Current Electricity

• Current (I): I = n A e v_d.

• Current Density (J): J = I / A = n e v_d.

• Resistance (R): R = ρL / A.

• Ohm's Law: J = σE or E = ρJ, and V = IR.

• Resistivity (ρ): ρ = m / (n e² τ).

• Mobility (μ): μ = v_d / E.

• Resistance of Stretched Wire: R ∝ L² (volume constant).

• Temperature Dependence: R = R₀ (1 + αΔT). R₀ is resistance at 0°C.

Also Check: JEE 2026 Error & Measurement One-Shot

Special Geometries for Resistance Calculation

Combination of Resistors

• Series: R_eq = R₁ + R₂ + ....

• Parallel: 1/R_eq = 1/R₁ + 1/R₂ + ....

• Current Divider (R₁ || R₂): I₁ = [R₂ / (R₁ + R₂)] * I_total.

• Polygons: Use Unitary Method. For n-sided polygon, resistance across an edge is R_eq = (n-1)R / n².

• Wheatstone Bridge (Balanced): R₁/R₂ = R₄/R₃. No current through middle resistor.

Kirchhoff's Laws

1. Current Law (KCL - Junction Rule): Sum of currents entering = Sum of currents leaving.

2. Voltage Law (KVL - Loop Rule): Sum of potential changes in a closed loop = 0.

Problems Involving Electric Bulbs

• Calculate R_bulb = (V_rated)² / P_rated. This resistance is constant.

• Actual power dissipated P_actual = I²R_bulb or V_actual² / R_bulb.

• In series, bulb with higher R (lower rated power) glows brighter.

Galvanometer Conversions

• Ammeter: Shunt (small S) in parallel. S = (I_G * R_G) / (I_A - I_G).

• Voltmeter: Large R in series. V = I_G * (R_G + R).

• Current Sensitivity (CS): CS = BNA / C.

• Voltage Sensitivity (VS): VS = BNA / CR.

Meter Bridge

Based on balanced Wheatstone bridge. R / X = L / (100 - L).

Parallel Plate Capacitor Basics

• Capacitance: C = ε₀A / d.

• Charge: Q = CV.

• Energy Stored: U = ½CV² = Q²/2C = ½QV.

• Energy Density: u = ½ ε₀ E².

Capacitor Combinations

Rules are inverse of resistors.

• Series: 1/C_eq = 1/C₁ + 1/C₂ + ... (charge Q is same).

• Parallel: C_eq = C₁ + C₂ + ... (voltage V is same).

• Wheatstone Bridge (Capacitors): Balanced if C₁C₃ = C₂C₄. Middle capacitor can be removed.

Capacitor with Dielectric (K)

• Capacitance: C_dielectric = K × C_air = K (ε₀A / d).

• K=1 for air, K=∞ for metals.

• Bound Charge (Q_b): Q_b = Q (1 - 1/K).

• Combinations of Dielectrics:

• In Series: Treat as capacitors in series.

• In Parallel: Treat as capacitors in parallel.

Sharing of Charge Between Capacitors

When two capacitors C₁, C₂ (initially V₁, V₂) are connected:

• Common Potential (Like Terminals): V_f = (C₁V₁ + C₂V₂) / (C₁ + C₂)

• Common Potential (Opposite Terminals): V_f = |C₁V₁ - C₂V₂| / (C₁ + C₂)

• Energy (Heat) Loss: ΔH = ½ [ (C₁C₂) / (C₁ + C₂) ] × (V₁ - V₂)² (for like terminals).

RC Circuits

• Time Constant: τ = RC.

• Charging:

• q(t) = CV (1 - e⁻ᵗ/τ).

• i(t) = (V/R) e⁻ᵗ/τ.

• At t=0, capacitor acts as short circuit (i=V/R).

• At t=∞, capacitor acts as open circuit (i=0).

• Discharging:

• q(t) = Q₀ e⁻ᵗ/τ.

• i(t) = (Q₀/RC) e⁻ᵗ/τ.

Magnetic Field Due to a Current-Carrying Straight Wire

• Finite Straight Wire: B = (μ₀I / 4πr) * (sin α + sin β). Field on axis is zero.

• Right-Hand Thumb Rule: Thumb = current, Fingers curl = B-field direction.

• Infinitely Long Wire: B = μ₀I / 2πr.

• Semi-Infinite Wire: B = μ₀I / 4πr.

Magnetic Field Due to a Circular Coil

• Center of Coil (N turns): B_center = μ₀NI / 2R.

• Axis of Coil (at distance x): B_axis = μ₀NIR² / 2(R² + x²)^(3/2).

• Right-Hand Curl Rule: Fingers curl = current, Thumb = B-field direction.

• Arc of a Loop (angle θ): B_arc = (μ₀I / 2R) * (θ / 2π).

Magnetic Field of Cylinders (Infinite Length)

• Hollow Cylinder: B_in = 0. B_out = μ₀I / 2πr.

• Solid Cylinder: B_out = μ₀I / 2πr. B_in = μ₀Ir / 2πR².

• Field is maximum at the surface (r=R) for a solid cylinder.

Magnetic Field of Solenoids and Toroids

• Ideal Solenoid: B_in = μ₀nI = μ₀NI / L. B_out = 0.

• Toroid: B = μ₀NI / 2πr (inside core). B_out = 0.

• Magnetic Medium (μᵣ): B_medium = μᵣ * B_vacuum.

Ampere's Circuital Law

∮ B ⋅ dl = μ₀ * I_enclosed. I_enclosed is current passing through the loop, with sign determined by right-hand rule.

Magnetic Force on a Moving Charge

• Lorentz Force: F = q(v × B). Magnitude F = |q|vB sin(θ).

• F is perpendicular to v and B.

• Magnetic force does no work, does not change speed or kinetic energy.

• Right-Hand Palm Rule: Fingers = v, Palm = B, Thumb = F. (Opposite for negative charges).

Motion of a Charge in a Uniform Magnetic Field

• v || B: Straight line path (F=0).

• v ⊥ B: Uniform circular motion.

• Radius (r): r = mv / qB = p / qB = √(2mKE) / qB = √(2mqV) / qB.

• Time Period (T): T = 2πm / qB (independent of v, r).

• Angular Frequency (ω): ω = qB / m.

• v at Arbitrary Angle: Helical path.

• Pitch: (v cosθ) * T = (v cosθ) * (2πm / qB).

Magnetic Force on a Current-Carrying Wire

• Formula: F = I (L_eq × B). L_eq is vector from start to end.

• Closed Loop in Uniform Field: Net force is zero.

Force Between Two Parallel Wires

• Same direction currents attract. Opposite direction currents repel.

• Force per Unit Length: F/L = (μ₀ * I₁ * I₂) / (2πr).

Magnetic Dipole Moment and Torque on a Current Loop

• Magnetic Dipole Moment (M): M = N * I * A.

• Torque (τ): τ = M × B. Magnitude τ = MB sin(θ).

• Potential Energy (U): U = -M ⋅ B.

• Time Period of Small Oscillation: T = 2π√(I / MB).

• Bar Magnets: Analogy to electric dipoles applies (k → μ₀/4π, p → M, E → B).

Moving Coil Galvanometer (MCG)

• Principle: BINA = Cφ. (Magnetic torque = Restoring torque). φ in radians.

• Current Sensitivity (CS): CS = BNA / C.

• Voltage Sensitivity (VS): VS = BNA / CR.

Magnetic Properties of Matter

• Net Field: B_net = μ_r * B_external.

• Susceptibility (χ): μ_r = 1 + χ.

• Classification:

• Diamagnetic: χ < 0, 0 ≤ μ_r < 1 (repelled).

• Paramagnetic: χ > 0 (small), μ_r > 1 (slightly attracted).

• Ferromagnetic: χ >> 1, μ_r >> 1 (strongly attracted).

Electromagnetic Induction (EMI)

• Magnetic Flux (Φ): Φ = BA cosθ (single surface). Φ_total = NBA cosθ (N turns). Unit: Weber (Wb).

• Faraday's Law: ε = -dΦ/dt. (Lenz's Law gives negative sign).

• Motional EMF (straight rod): ε = vBL (if v, B, L are mutually perpendicular).

• Right-Hand Rule for Polarity: Fingers = v, Palm = B, Thumb = Positive terminal.

• Rotational EMF (rod rotating): ε = ½ BωL² (rod rotates about one end). ε = ½ Bω(L₂² - L₁²) (arbitrary axis).