Padikam Lessons Library | Kerala SCERT & CBSE NCERT Textbooks

SCERT KeralaClass 12Physics

Physics

14 chapters PDF / 103 KB

ORIGINAL STUDY COMPANION PADIKAM CLASS 12 | SCIENCE Physics Kerala SCERT / prescribed NCERT core lessons 14 chapter lessons Quick explanations, core points, exam practice and chapter-specific notation in one consistent format. Padikam explanations are independently written. Official textbooks are used as the coverage map, chapter sequence and terminology reference. PADIKAM | KERALA CLASS 12 1

Contents 01 Electric Charges and Fields 08 Electromagnetic Waves 02 Electrostatic Potential and Capacitance 09 Ray Optics and Optical Instruments 03 Current Electricity 10 Wave Optics 04 Moving Charges and Magnetism 11 Dual Nature of Radiation and Matter 05 Magnetism and Matter 12 Atoms 06 Electromagnetic Induction 13 Nuclei 07 Alternating Current 14 Semiconductor Electronics: Materials, Devices and Simple Circuits Study rhythm Read the quick explanation, recall the core points aloud, then answer the prompts without looking back. Use the official textbook links for full prescribed readings, activities and diagrams. Textbook and verification links

CHAPTER 01 Electric Charges and Fields Quick understanding Electric charge produces an electric field; superposition lets us add the effects of many charges without changing the contribution of each one. Core points Check your learning Charge is quantised and conserved. Explain the central idea of Electric Charges and Fields in your own words. Coulomb force acts along the line joining two point charges. Apply one idea from Electric Charges and Fields to a textbook-style example or Gauss law is most useful when symmetry makes the source. field constant on a surface. Equation and notation F = (1 / 4πε₀) (q₁q₂ / r²) E = F / q₀ ΦE = ∮ E · dA = q(enclosed) / ε₀ SYMBOLS AND UNITS F: electrostatic force (N) q₁, q₂, q₀: electric charge (C) r: separation (m) E: electric field (N C⁻¹) ΦE: electric flux (N m² C⁻¹) ε₀: permittivity of free space (F m⁻¹) One-line recall Charge is quantised and conserved. PADIKAM | KERALA CLASS 12 3

CHAPTER 02 Electrostatic Potential and Capacitance Quick understanding Potential measures electric potential energy per unit charge, while a capacitor stores separated charge and energy. Core points Check your learning Potential is a scalar, so contributions add Explain the central idea of Electrostatic algebraically. Potential and Capacitance in your own words. An equipotential surface is everywhere perpendicular to the electric field. Apply one idea from Electrostatic Potential and Capacitance to a textbook- Dielectrics increase capacitance by reducing the style example or source. effective field. Equation and notation V = W / q C = Q / V C(parallel plate) = ε₀A / d U = ½CV² SYMBOLS AND UNITS V: electric potential (V) W, U: work or stored energy (J) Q, q: charge (C) C: capacitance (F) A: plate area (m²) d: plate separation (m) One-line recall Potential is a scalar, so contributions add algebraically. PADIKAM | KERALA CLASS 12 4

CHAPTER 03 Current Electricity Quick understanding A steady current is the organised drift of charge through a conductor under an electric field. Core points Check your learning Ohm law describes linear conductors at fixed Explain the central idea of Current physical conditions. Electricity in your own words. Resistivity is a material property; resistance also Apply one idea from Current Electricity to depends on dimensions. a textbook-style example or source. Kirchhoff rules express conservation of charge and energy in circuits. Equation and notation I = Q / t V = IR R = ρl / A P = VI = I²R = V² / R SYMBOLS AND UNITS I: electric current (A) Q: charge (C) t: time (s) V: potential difference (V) R: resistance (Ω) ρ: resistivity (Ω m) l: conductor length (m) A: cross-sectional area (m²) P: electric power (W) One-line recall Ohm law describes linear conductors at fixed physical conditions. PADIKAM | KERALA CLASS 12 5

CHAPTER 04 Moving Charges and Magnetism Quick understanding Moving charges create magnetic fields and experience forces that depend on velocity, field strength and direction. Core points Check your learning The magnetic force is perpendicular to both velocity Explain the central idea of Moving and field. Charges and Magnetism in your own words. A current element follows the Biot-Savart law. Apply one idea from Moving Charges Parallel currents exert measurable forces on each and Magnetism to a textbook-style other. example or source. Equation and notation F = q(v × B) F = I(l × B) r = mv / qB B(long wire) = μ₀I / 2πr SYMBOLS AND UNITS F: magnetic force (N) q: charge (C) v: velocity (m s⁻¹) B: magnetic flux density (T) I: current (A) l: conductor length vector (m) r: orbit radius or distance (m) m: particle mass (kg) μ₀: permeability of free space (H m⁻¹) One-line recall The magnetic force is perpendicular to both velocity and field. PADIKAM | KERALA CLASS 12 6

CHAPTER 05 Magnetism and Matter Quick understanding A magnetic dipole responds to an external field, and magnetic materials differ through the way their internal moments align. Core points Check your learning A bar magnet is well modelled as a dipole. Explain the central idea of Magnetism and Matter in your own words. Earth has a measurable magnetic field with declination and dip. Apply one idea from Magnetism and Matter to a textbook-style example or Diamagnetic, paramagnetic and ferromagnetic source. substances respond differently. Equation and notation τ = m × B U = -m · B B(axial dipole) = (μ₀ / 4π)(2m / r³) SYMBOLS AND UNITS τ: torque (N m) m: magnetic dipole moment (A m²) B: magnetic flux density (T) U: potential energy (J) r: distance from dipole centre (m) One-line recall A bar magnet is well modelled as a dipole. PADIKAM | KERALA CLASS 12 7

CHAPTER 06 Electromagnetic Induction Quick understanding A changing magnetic flux produces an emf whose direction opposes the change that causes it. Core points Check your learning Faraday law gives the magnitude of induced emf. Explain the central idea of Electromagnetic Induction in your own Lenz law fixes direction and expresses energy words. conservation. Apply one idea from Electromagnetic Self and mutual inductance quantify flux linkage per Induction to a textbook-style example or current change. source. Equation and notation ΦB = ∫ B · dA ε = -N dΦB / dt εL = -L dI / dt U = ½LI² SYMBOLS AND UNITS ΦB: magnetic flux (Wb) B: magnetic flux density (T) A: area (m²) ε: induced emf (V) N: number of turns t: time (s) L: inductance (H) I: current (A) One-line recall Faraday law gives the magnitude of induced emf. PADIKAM | KERALA CLASS 12 8

CHAPTER 07 Alternating Current Quick understanding Alternating current varies periodically, so rms values and phase relations are used to compare its effects with direct current. Core points Check your learning A resistor, inductor and capacitor produce different Explain the central idea of Alternating phase relations. Current in your own words. Impedance combines resistance and reactance. Apply one idea from Alternating Current to a textbook-style example or source. Resonance occurs when inductive and capacitive reactances cancel. Equation and notation v = Vₘ sin ωt Vᵣₘₛ = Vₘ / √2 Z = √(R² + (Xₗ - Xc)²) ω₀ = 1 / √(LC) SYMBOLS AND UNITS v, Vₘ, Vᵣₘₛ: voltage values (V) ω: angular frequency (rad s⁻¹) t: time (s) Z, R, Xₗ, Xc: impedance, resistance and reactances (Ω) L: inductance (H) C: capacitance (F) One-line recall A resistor, inductor and capacitor produce different phase relations. PADIKAM | KERALA CLASS 12 9

CHAPTER 08 Electromagnetic Waves Quick understanding Time-varying electric and magnetic fields sustain each other and travel through space as transverse electromagnetic waves. Core points Check your learning Electromagnetic waves need no material medium. Explain the central idea of Electromagnetic Waves in your own Electric field, magnetic field and propagation words. direction are mutually perpendicular. Apply one idea from Electromagnetic All bands share the same vacuum speed but differ in Waves to a textbook-style example or frequency and wavelength. source. Equation and notation c = 1 / √(μ₀ε₀) c = νλ E₀ / B₀ = c SYMBOLS AND UNITS c: speed of light in vacuum (m s⁻¹) μ₀: permeability of free space (H m⁻¹) ε₀: permittivity of free space (F m⁻¹) ν: frequency (Hz) λ: wavelength (m) E₀: electric-field amplitude (V m⁻¹) B₀: magnetic-field amplitude (T) One-line recall Electromagnetic waves need no material medium. PADIKAM | KERALA CLASS 12 10

CHAPTER 09 Ray Optics and Optical Instruments Quick understanding Geometrical optics follows rays through reflection and refraction to locate images and analyse instruments. Core points Check your learning Use the Cartesian sign convention consistently. Explain the central idea of Ray Optics and Optical Instruments in your own Total internal reflection requires incidence from words. denser to rarer medium above the critical angle. Apply one idea from Ray Optics and The eye, microscope and telescope use Optical Instruments to a textbook-style combinations of lenses. example or source. Equation and notation 1/f = 1/v - 1/u m = hᵢ / hₒ = v / u n₁ sin i = n₂ sin r Power P = 1/f SYMBOLS AND UNITS f, u, v: focal length, object distance and image distance m: magnification, dimensionless (m) hᵢ, hₒ: image and object height (m) n₁, n₂: refractive indices, dimensionless i, r: angles of incidence and refraction P: lens power (D) One-line recall Use the Cartesian sign convention consistently. PADIKAM | KERALA CLASS 12 11

CHAPTER 10 Wave Optics Quick understanding Wave optics explains interference, diffraction and polarisation by superposing coherent wave disturbances. Core points Check your learning Huygens principle constructs a new wavefront from Explain the central idea of Wave Optics secondary wavelets. in your own words. Stable fringes require coherent sources. Apply one idea from Wave Optics to a textbook-style example or source. Polarisation demonstrates the transverse nature of light. Equation and notation Path difference Δ = d sin θ β = λD / d I = I₁ + I₂ + 2√(I₁I₂) cos φ SYMBOLS AND UNITS Δ: path difference (m) d: slit separation (m) θ: observation angle β: fringe width (m) λ: wavelength (m) D: screen distance (m) I, I₁, I₂: intensities (W m⁻²) φ: phase difference (rad) One-line recall Huygens principle constructs a new wavefront from secondary wavelets. PADIKAM | KERALA CLASS 12 12

CHAPTER 11 Dual Nature of Radiation and Matter Quick understanding Radiation and matter reveal wave or particle behaviour depending on how they are observed. Core points Check your learning The photoelectric effect supports quantised photon Explain the central idea of Dual Nature of energy. Radiation and Matter in your own words. Stopping potential measures maximum photoelectron Apply one idea from Dual Nature of kinetic energy. Radiation and Matter to a textbook-style example or source. de Broglie wavelength associates a wave with moving matter. Equation and notation E = hν = hc / λ Kₘₐₓ = hν - φ = eV₀ λ = h / p SYMBOLS AND UNITS E: photon energy (J) h: Planck constant (J s) ν: frequency (Hz) c: light speed (m s⁻¹) λ: wavelength (m) Kₘₐₓ: maximum kinetic energy (J) φ: work function (J) e: elementary charge (C) V₀: stopping potential (V) p: momentum (kg m s⁻¹) One-line recall The photoelectric effect supports quantised photon energy. PADIKAM | KERALA CLASS 12 13

CHAPTER 12 Atoms Quick understanding Atomic spectra arise because electrons in atoms occupy discrete energy states and exchange photons during transitions. Core points Check your learning Rutherford scattering established a small positive Explain the central idea of Atoms in your nucleus. own words. Bohr quantisation explains the hydrogen spectrum. Apply one idea from Atoms to a textbook- style example or source. A lower energy level is more tightly bound. Equation and notation mvr = nh / 2π Eₙ = -13.6 / n² eV hν = |E₂ - E₁| SYMBOLS AND UNITS m: electron mass (kg) v: electron speed (m s⁻¹) r: orbit radius (m) n: principal quantum number h: Planck constant (J s) Eₙ: energy of nth level (eV) ν: photon frequency (Hz) One-line recall Rutherford scattering established a small positive nucleus. PADIKAM | KERALA CLASS 12 14

CHAPTER 13 Nuclei Quick understanding Nuclear stability depends on the balance of forces and is measured through mass defect, binding energy and radioactive change. Core points Check your learning Isotopes share atomic number but differ in neutron Explain the central idea of Nuclei in your number. own words. Binding energy per nucleon helps compare stability. Apply one idea from Nuclei to a textbook- style example or source. Radioactive decay is probabilistic for one nucleus but predictable for a large sample. Equation and notation E = Δmc² N = N₀e⁻λt T½ = ln 2 / λ Activity A = λN SYMBOLS AND UNITS E: binding energy (J) Δm: mass defect (kg) c: light speed (m s⁻¹) N, N₀: number of undecayed nuclei λ: decay constant (s⁻¹) t: time (s) T½: half-life (s) A: activity (Bq) One-line recall Isotopes share atomic number but differ in neutron number. PADIKAM | KERALA CLASS 12 15

CHAPTER 14 Semiconductor Electronics: Materials, Devices and Simple Circuits Quick understanding Controlled charge carriers make semiconductor junctions useful for rectification, regulation and digital switching. Core points Check your learning Doping creates n-type or p-type material without Explain the central idea of giving the crystal a net charge. Semiconductor Electronics: Materials, Devices and Simple Circuits in your own Forward bias lowers a junction barrier; reverse bias words. raises it. Apply one idea from Semiconductor Logic gates represent Boolean decisions with Electronics: Materials, Devices and voltage levels. Simple Circuits to a textbook-style example or source. Equation and notation I = I₀(e^(V/ηVₜ) - 1) Vₒ ≈ Vᵢ - V(diode) A AND B = A · B; A OR B = A + B SYMBOLS AND UNITS I: diode current (A) I₀: reverse saturation current (A) V: junction voltage (V) η: ideality factor, dimensionless Vₜ: thermal voltage (V) Vᵢ, Vₒ: input and output voltage (V) A, B: Boolean inputs 0 or 1 One-line recall Doping creates n-type or p-type material without giving the crystal a net charge. PADIKAM | KERALA CLASS 12 16