Class 11 Physics Notes (FSc Part I) — All Chapters with Key Formulas (2026)

These FSc Part I (class 11) physics notes cover all eleven chapters. Each section lists the key formulas, important definitions, and concepts you must know for board exams and MDCAT. Use these as a revision tool after studying from your textbook.

Chapter 1: Measurements

Key formulas and concepts:

• Dimensions: [Force] = [MLT⁻²], [Energy] = [ML²T⁻²], [Power] = [ML²T⁻³], [Pressure] = [ML⁻¹T⁻²]
• Percentage uncertainty = (least count / measured value) × 100
• For a quantity Z = Aⁿ × Bᵐ: %ΔZ = n(%ΔA) + m(%ΔB)
• Dimensional analysis: use to verify equations, derive relations, and convert units

Chapter 2: Vectors and Equilibrium

Key formulas:

• Rectangular components: Ax = A cos θ, Ay = A sin θ
• Magnitude: A = √(Ax² + Ay²)
• Dot product: A·B = AB cos θ (scalar result — used for work: W = F·d)
• Cross product: A×B = AB sin θ n̂ (vector result — used for torque: τ = r×F)
• First condition of equilibrium: ΣF = 0
• Second condition of equilibrium: Στ = 0

Chapter 3: Motion and Force

Key formulas:

• Equations of motion (constant acceleration): v = v₀ + at, s = v₀t + ½at², v² = v₀² + 2as
• Projectile motion — horizontal range: R = v₀² sin 2θ / g
• Maximum height: H = v₀² sin²θ / 2g
• Time of flight: T = 2v₀ sin θ / g
• Maximum range occurs at θ = 45°
• Newton's second law: F = dp/dt = ma (for constant mass)

Chapter 4: Work and Energy

Key formulas:

• Work: W = F·d = Fd cos θ
• Kinetic energy: KE = ½mv²
• Work-energy theorem: W_net = ΔKE
• Gravitational PE: PE = mgh
• Elastic PE: PE = ½kx²
• Power: P = W/t = F·v
• Elastic collision (1D): both momentum and KE conserved
• Inelastic collision: momentum conserved, KE not conserved

Chapter 5: Circular Motion

Key formulas:

• Angular velocity: ω = Δθ/Δt = 2πf = 2π/T
• Linear and angular: v = rω, a = rα
• Centripetal acceleration: ac = v²/r = rω²
• Centripetal force: Fc = mv²/r = mrω²
• Banking angle: tan θ = v²/rg
• Orbital velocity: v₀ = √(gR) near Earth surface

Chapter 6: Fluid Dynamics

Key formulas:

• Equation of continuity: A₁v₁ = A₂v₂
• Bernoulli's equation: P + ½ρv² + ρgh = constant
• Stokes' law: F = 6πηrv (viscous drag on a sphere)
• Terminal velocity: vt = 2r²(ρ − σ)g / 9η

Chapter 7: Oscillations

Key formulas:

• SHM displacement: x = x₀ sin(ωt + φ)
• SHM velocity: v = x₀ω cos(ωt + φ); maximum velocity = x₀ω
• SHM acceleration: a = −ω²x
• Mass-spring system: T = 2π√(m/k)
• Simple pendulum: T = 2π√(l/g)
• Total energy in SHM: E = ½kx₀² = ½mω²x₀² (constant)
• At any point: KE + PE = ½kx₀²

Chapter 8: Waves

Key formulas:

• Wave equation: v = fλ
• Stationary waves: nodes (zero displacement), antinodes (maximum displacement)
• Beats: f_beat = |f₁ − f₂|
• Doppler effect: f' = f(v ± v_observer) / (v ∓ v_source)

Chapter 9: Physical Optics

Key formulas:

• Young's double slit: fringe spacing Δy = λL/d
• Constructive interference: path difference = nλ
• Destructive interference: path difference = (n + ½)λ
• Diffraction grating: d sin θ = nλ

Chapter 10: Optical Instruments

Key formulas:

• Simple microscope magnification: M = 1 + d/f (d = 25 cm, near point)
• Compound microscope: M = (L/fo)(d/fe) approximately
• Astronomical telescope (normal adjustment): M = fo/fe

Chapter 11: Heat and Thermodynamics

Key formulas:

• Ideal gas law: PV = nRT (R = 8.314 J/mol·K)
• Also: PV = NkT (k = 1.38 × 10⁻²³ J/K)
• KE of gas molecule: KE = (3/2)kT
• First law: ΔQ = ΔU + W (heat = internal energy change + work done by gas)
• Work by gas: W = PΔV (at constant pressure)
• Molar specific heats: Cp − Cv = R
• Adiabatic process: PVᵞ = constant (γ = Cp/Cv)
• Carnot efficiency: η = 1 − T_cold/T_hot
• Entropy change: ΔS = ΔQ/T

How to Use These Notes

These notes summarise the most important formulas and concepts. For full understanding, always refer to your Punjab Textbook Board physics textbook. After revising each chapter, practise MCQs on HighYield to test your application skills — knowing a formula and applying it under time pressure are two different skills.