50 Diagrams · 14 Chapters

Important Diagrams
CBSE Physics XII

Every standard diagram you need for board exams, organized chapter-wise with clear labels and annotations.

1

Electric Charges & Fields

+q E E Field lines radiate outward from +q
Fig 1.1 · Chapter 1
Electric field lines of a positive point charge
+ − p (dipole moment) Field lines from + to −
Fig 1.2 · Chapter 1
Electric field lines of a dipole
+ + + − − − E (uniform) Uniform electric field between parallel plates +σ −σ
Fig 1.3 · Chapter 1
Uniform electric field between two parallel plates
2

Electrostatic Potential & Capacitance

+q V₁ V₂ V₃ V₁ > V₂ > V₃ > V₄ Equipotential Field lines
Fig 2.1 · Chapter 2
Equipotential surfaces for a point charge
Without Dielectric + − C = ε₀A/d d With Dielectric + − K − − − − + + + + C' = Kε₀A/d Dielectric constant K Capacitance increases by factor K with dielectric
Fig 2.2 · Chapter 2
Parallel plate capacitor with and without dielectric slab
Capacitors in Series C₁ C₂ C₃ A B 1/C = 1/C₁ + 1/C₂ + 1/C₃ Capacitors in Parallel C₁ C₂ C₃ A B C = C₁ + C₂ + C₃
Fig 2.3 · Chapter 2
Capacitors in series and parallel combinations
3

Current Electricity

G A B C D P Q R S Balance: P/Q = R/S
Fig 3.1 · Chapter 3
Wheatstone Bridge circuit diagram
A B 0 50 100 R S G J (Jockey) l cm (100 − l) cm E R/S = l/(100 − l)
Fig 3.2 · Chapter 3
Meter Bridge (practical Wheatstone Bridge)
A B E (Driver) Rh E₁ E₂ Two-way Key G Jockey J l₁ l₂ E₁/E₂ = l₁/l₂ Null point at l₁ for E₁, at l₂ for E₂
Fig 3.3 · Chapter 3
Potentiometer: comparing EMFs of two cells
V I O Ohmic (Resistor) V = IR (linear) Non-ohmic (e.g., Filament) V-I characteristics: Ohmic vs Non-ohmic conductors
Fig 3.4 · Chapter 3
V-I characteristics of ohmic and non-ohmic conductors
4

Moving Charges & Magnetism

I (upward) B B Cross-section Out (dot) In (cross) Right-hand thumb rule: Thumb along I, fingers curl along B
Fig 4.1 · Chapter 4
Magnetic field around a straight current-carrying conductor
I B Axis of loop Field resembles a magnetic dipole at large distances
Fig 4.2 · Chapter 4
Magnetic field of a circular current loop
N S Current I in coil B = μ₀nI (uniform inside) Field is uniform inside, resembles bar magnet outside
Fig 4.3 · Chapter 4
Solenoid: uniform magnetic field inside
N S Iron Core Coil Spring Scale T₁ T₂ Torque: τ = NIAB; Deflection: θ = NIAB/k
Fig 4.4 · Chapter 4
Moving Coil Galvanometer (schematic)
D₁ D₂ Source Exit beam B (into page) Oscillating E field in gap f = qB/(2πm) (cyclotron frequency)
Fig 4.5 · Chapter 4
Cyclotron: D-shaped dees with spiral particle path
5

Magnetism & Matter

N S Inside: S to N
Fig 5.1 · Chapter 5
Bar magnet field lines (N to S externally)
Bar Magnet N S Solenoid N S Identical external field patterns vs
Fig 5.2 · Chapter 5
Bar magnet vs solenoid: field line comparison
6

Electromagnetic Induction

N S ABCD coil rotation Slip Rings Brush Brush R B field e = NBAω sin(ωt) = e₀ sin(ωt)
Fig 6.1 · Chapter 6
AC Generator with slip rings and brushes
Laminated Iron Core Nₚ Nₛ AC Load Φ (flux) Primary Secondary Vₛ/Vₚ = Nₛ/Nₚ (Step-up: Nₛ > Nₚ)
Fig 6.2 · Chapter 6
Step-up Transformer: primary, iron core, secondary
Metal Conductor Plate × × × × × × × × × B (into page) Eddy Eddy Changing B induces swirling eddy currents Eddy currents oppose change in flux (Lenz's Law)
Fig 6.3 · Chapter 6
Eddy currents in a metal conductor
7

Alternating Current

R L C V~ I V = V₀ sin(ωt) Z = √[R² + (Xₗ − X⁾)²]
Fig 7.1 · Chapter 7
LCR Series Circuit with AC source
O Vᴘ = IR I (reference) Vᴧ = IXᴧ Vᴄ = IXᴄ Vᴧ−Vᴄ V φ tan φ = (Xᴧ − Xᴄ)/R Shown: Xᴧ > Xᴄ (inductive circuit, V leads I)
Fig 7.2 · Chapter 7
Phasor diagram for series LCR circuit
ω (frequency) I O ω₀ = 1/√LC Iₘₙₓ Low R (sharp) High R (broad)
Fig 7.3 · Chapter 7
Resonance curve: current vs frequency in LCR circuit
V I φ V cosφ V sinφ Power Factor = cos φ = R/Z P = Vᵢᵣᵤᵥ Iᵢᵣᵤᵥ cos φ At resonance: φ = 0, cosφ = 1, P is maximum
Fig 7.4 · Chapter 7
Power factor: phase angle between V and I
9

Ray Optics & Optical Instruments

P F C Object Image (real, inverted, diminished) Object beyond C: image between F and C
Fig 9.1 · Chapter 9
Concave mirror: image formation (object beyond C)
F₁ F₂ 2F₁ 2F₂ O Object Image (real, inverted, diminished) Object beyond 2F: image between F and 2F
Fig 9.2 · Chapter 9
Convex lens: ray diagram (three standard rays)
A Normal Incident ray Emergent ray i e r₁ r₂ δ δ = (i + e) − A A = r₁ + r₂
Fig 9.3 · Chapter 9
Refraction through a prism showing angle of deviation
Rarer medium Denser medium Normal i < iᶜ i = iᶜ r = 90° i > iᶜ TIR iᶜ sin iᶜ = n₂/n₁ (n₁ > n₂)
Fig 9.4 · Chapter 9
Total Internal Reflection at critical angle
Objective (fₒ small) Eyepiece (fₑ larger) Object fₒ Intermediate image (real, inverted) fₑ Eye M = mₒ × mₑ = (L/fₒ)(1 + D/fₑ)
Fig 9.5 · Chapter 9
Compound Microscope: objective, eyepiece, image formation
Objective (fₒ large) Eyepiece (fₑ small) From distant object Image at Fₒ = Fₑ Eye fₒ fₑ M = fₒ/fₑ, Length L = fₒ + fₑ
Fig 9.6 · Chapter 9
Astronomical Telescope in normal adjustment
n₁ n₂ O C P I i r u v R n₂/v − n₁/u = (n₂ − n₁)/R
Fig 9.7 · Chapter 9
Refraction at a convex spherical surface
10

Wave Optics

S S₁ S₂ Screen Central max d D Fringe width: β = λD/d
Fig 10.1 · Chapter 10
Young's Double Slit Experiment (YDSE)
sinθ I Central Maximum 2nd 2nd 1st 1st Minima: a sinθ = nλ (n = 1,2,3...) Central max width = 2λD/a
Fig 10.2 · Chapter 10
Single slit diffraction: intensity distribution
Spherical Point source Plane From distant source Cylindrical Line source
Fig 10.3 · Chapter 10
Types of wavefronts: spherical, plane, cylindrical
11

Dual Nature of Radiation & Matter

Evacuated glass tube C (Emitter) A (Collector) hν (Light) e⁻ e⁻ e⁻ e⁻ A Variable V Kₘₙₓ = hν − φ
Fig 11.1 · Chapter 11
Photoelectric effect experimental setup
ν V₀ O ν₀ (threshold) −φ/e slope = h/e Metal 2 Metal 1 V₀ = (h/e)ν − φ/e
Fig 11.2 · Chapter 11
Stopping potential vs frequency graph
V I O −V₀ Retarding potential I₃ (high) I₂ I₁ (low) −V₀ (same for all) V₀ depends on frequency, not intensity
Fig 11.3 · Chapter 11
Photocurrent vs collector plate potential (different intensities)
12

Atoms

n=1 n=2 n=3 n=4 n=5 n=6 n=∞ −13.6 eV −3.4 eV −1.51 eV −0.85 eV −0.54 eV 0 eV Lyman (UV) Balmer (Visible) Paschen (IR) Hydrogen Atom Energy Levels Eₙ = −13.6/n² eV
Fig 12.1 · Chapter 12
Bohr model: energy levels and spectral series
α Source Gold Foil + ZnS Screen Most pass through Few deflected Very few back-scattered Most of atom is empty space +ve charge concentrated in tiny nucleus b (impact parameter) determines deflection angle
Fig 12.2 · Chapter 12
Rutherford's alpha particle scattering experiment
13

Nuclei

Mass Number A BE/A (MeV) 0 2 4 6 8 10 ²H ⁴He ¹²C ¹⁶O ⁵⁶Fe (most stable) ²³⁸U Fusion region Fission region 20 60 120 180 240 Both fusion and fission move toward higher BE/A (Fe-56 peak)
Fig 13.1 · Chapter 13
Binding Energy per Nucleon vs Mass Number
n ²³⁵U + n ²³⁶U* ¹⁴¹Ba (Fragment) ⁹²Kr (Fragment) n n n + Energy (~200 MeV) 3 neutrons ²³⁵U + n → ¹⁴¹Ba + ⁹²Kr + 3n + Energy
Fig 13.2 · Chapter 13
Nuclear fission of Uranium-235
14

Semiconductor Electronics

p-type + + + + + − − − − − − − n-type − − − − − + + + + + + + Depletion Region E (barrier field) Vᵇ ≈ 0.7V (Si), 0.3V (Ge)
Fig 14.1 · Chapter 14
p-n junction formation with depletion region
p n Narrow + − V (Forward) Current flows (I) holes → ← e⁻
Fig 14.2 · Chapter 14
Forward bias: depletion region narrows, current flows
p n Wide depletion − + V (Reverse) No current (negligible I) ← holes e⁻ →
Fig 14.3 · Chapter 14
Reverse bias: depletion region widens, no current
V I (mA) O Forward Vᵊ (0.7V Si) Reverse −V Iₛ (μA) +V −I
Fig 14.4 · Chapter 14
V-I characteristics of a p-n junction diode
V I O Forward −Vᵪ (Breakdown) Sharp increase in reverse I Zener symbol
Fig 14.5 · Chapter 14
Zener diode V-I characteristics (breakdown region)
Vᵢᵤ Rₛ Zener Vᵪ Iᵪ Rᴧ Vₒ = Vᵪ (constant) Vₒ = Vᵪ (constant regardless of Vᵢᵤ variation)
Fig 14.6 · Chapter 14
Zener diode as voltage regulator circuit
B C E NPN Vᵢᵤ Vᵇᵇ Rᶜ Vᶜᶜ Vₒ Common Emitter: Aᵥ = β(Rᶜ/Rᵢᵤ)
Fig 14.7 · Chapter 14
Common Emitter NPN transistor amplifier
Input Characteristics Vᵇᵉ Iᵇ Vᶜᵉ=const Output Characteristics Vᶜᵉ Iᶜ Iᵇ₃ Iᵇ₂ Iᵇ₁ Iᵇ=0 Saturation Active region β = ΔIᶜ/ΔIᵇ (at const Vᶜᵉ)
Fig 14.8 · Chapter 14
Input and Output characteristics of CE transistor
AND A B Y=A.B ABY 000 010 100 111 OR A B Y=A+B ABY 000 011 101 111 NOT A Y=A' AY 01 10 NAND A B Y=(A.B)' ABY 001 011 101 110 NOR A B Y=(A+B)' ABY 001 010 100 110 XOR A B Y=A⊕B ABY 000 011 101 110 NAND and NOR are Universal Gates Any logic circuit can be built using only NAND or only NOR gates De Morgan's: (A.B)' = A'+B' and (A+B)' = A'.B'
Fig 14.9 · Chapter 14
Logic gate symbols with truth tables: AND, OR, NOT, NAND, NOR, XOR