FAD1022 — FINAL EXAM SCOPE (Priority Topics)
Last Updated: 2026-05-04
Based on: Lecture 45, FAD1022 L4-L5, Tutorial 15, and Exam Intel
Status: HIGH PRIORITY — These topics appear every exam
PRIORITY 1: Modern Physics (SECTION B — Guaranteed)
Photoelectric Effect (THE EXAM FAVORITE)
Appears in: Section B (structured, multi-part, high marks)
Frequency: Every exam without fail
Source: Tutorial 15 Q2, Lecture 45
The 3 Cases You MUST Know:
| Case | Given | Formula | What to Find |
|---|---|---|---|
| Case 1 | Two $(f, V_s)$ pairs | $eV_s = hf - \phi$ | Solve simultaneously for $h$ AND $\phi$ |
| Case 2 | Photon energy $E$ and $K_{max}$ | $\phi = E - K_{max}$ | Work function only |
| Case 3 | Threshold frequency $f_0$ | $\phi = hf_0$ | Work function directly |
Key Formulas: $$K_{max} = hf - \phi = eV_s = \frac{1}{2}m_e v_{max}^2$$
Strategy for Case 1:
- Write $eV_{s1} = hf_1 - \phi$ ... (1)
- Write $eV_{s2} = hf_2 - \phi$ ... (2)
- Subtract: $(V_{s2} - V_{s1})e = (f_2 - f_1)h$
- Solve for $h$, then substitute back for $\phi$
Constants to Memorize:
- $h = 6.63 \times 10^{-34}$ J·s
- $e = 1.60 \times 10^{-19}$ C
- $m_e = 9.11 \times 10^{-31}$ kg
- $c = 3.0 \times 10^{8}$ m/s
de Broglie Wavelength
Source: Tutorial 15 Q4, Lecture 45
Formulas: $$\lambda = \frac{h}{p} = \frac{h}{mv} = \frac{h}{\sqrt{2m(KE)}}$$
When to use which:
- Given velocity $v$ → Use $\lambda = \frac{h}{mv}$
- Given kinetic energy → Use $\lambda = \frac{h}{\sqrt{2m(KE)}}$
Unit Conversions:
- $KE$ in eV → Multiply by $1.6 \times 10^{-19}$ to get joules
- Answer typically in nanometers ($10^{-9}$ m) or angstroms ($10^{-10}$ m)
Heisenberg Uncertainty Principle
Source: Tutorial 15 Q5, Lecture 45
Formula: $$\Delta x \cdot \Delta p \geq \frac{h}{4\pi}$$
Minimum Uncertainty (use this for calculations): $$\Delta p_{min} = \frac{h}{4\pi \cdot \Delta x}$$
Common Variation:
- Given $\Delta x$, find $\Delta v$: $\Delta v = \frac{\Delta p}{m} = \frac{h}{4\pi m \cdot \Delta x}$
Photon Momentum
Source: Tutorial 15 Q3, Lecture 45
Formula: $$p = \frac{h}{\lambda} = \frac{E}{c}$$
Quick Check:
- Higher frequency → Higher momentum
- Shorter wavelength → Higher momentum
Compton Effect (Less Common but Possible)
Source: Lecture 45
Formula: $$\Delta \lambda = \lambda' - \lambda = \frac{h}{m_e c}(1 - \cos\theta)$$
Compton Wavelength: $$\frac{h}{m_e c} = 2.43 \times 10^{-12} \text{ m}$$
Key Points:
- Maximum shift at $\theta = 180°$: $\Delta\lambda_{max} = \frac{2h}{m_e c}$
- Photon loses energy → wavelength increases
- Proof that photons have momentum
PRIORITY 2: Electrostatics (Gauss's Law)
Gauss's Law Applications
Source: FAD1022 L4-L5
| Configuration | Electric Field | Key Point |
|---|---|---|
| Point charge at distance $r$ | $E = \frac{kQ}{r^2}$ | Inverse square law |
| Line charge at distance $r$ | $E = \frac{\lambda}{2\pi r \varepsilon_0}$ | $E \propto \frac{1}{r}$ |
| Infinite plane | $E = \frac{\sigma}{2\varepsilon_0}$ | Constant! |
| Parallel plates (between) | $E = \frac{\sigma}{\varepsilon_0}$ | Uniform field |
| Parallel plates (outside) | $E = 0$ | Fields cancel |
| Conductor surface | $E = \frac{\sigma}{\varepsilon_0}$ | Just outside |
| Inside conductor | $E = 0$ | Equilibrium |
Conductors in Electrostatic Equilibrium
Source: FAD1022 L5
Key Properties:
- $E = 0$ inside conductor
- All excess charge on outer surface
- $E \perp$ to surface just outside
- $E = \frac{\sigma}{\varepsilon_0}$ at surface
PRIORITY 3: Electric Potential
Formulas
Source: FAD1022 L5
| Quantity | Formula |
|---|---|
| Potential from point charge | $V = \frac{kQ}{r}$ |
| Potential energy | $U = qV = \frac{kqQ}{r}$ |
| Work to move charge | $W = q\Delta V$ |
Superposition (Scalar!): $$V_{total} = \sum_i \frac{kq_i}{r_i}$$
Quick Reference: Constants
| Constant | Symbol | Value |
|---|---|---|
| Planck's constant | $h$ | $6.63 \times 10^{-34}$ J·s |
| Elementary charge | $e$ | $1.60 \times 10^{-19}$ C |
| Speed of light | $c$ | $3.0 \times 10^{8}$ m/s |
| Electron mass | $m_e$ | $9.11 \times 10^{-31}$ kg |
| Coulomb constant | $k$ | $8.99 \times 10^{9}$ N·m²/C² |
| Permittivity of free space | $\varepsilon_0$ | $8.85 \times 10^{-12}$ C²/(N·m²) |
| Compton wavelength | $\frac{h}{m_ec}$ | $2.43 \times 10^{-12}$ m |
| $hc$ | — | $1.24 \times 10^{-6}$ eV·m = 1240 eV·nm |
Exam Strategy
Section B — Modern Physics (Priority Order)
- Photoelectric Effect (75% chance) — Master the 3 cases
- de Broglie Wavelength (50% chance) — Watch unit conversions
- Heisenberg Uncertainty (40% chance) — Remember $\frac{h}{4\pi}$
- Compton Effect (25% chance) — Know the formula
Section A — Quick Calculations
- Electric flux through surfaces
- Gauss's Law applications
- Electric potential from multiple charges
- Photon momentum/energy conversions
Time Allocation
- Section A: 1-2 minutes per mark
- Section B: 5-10 minutes for photoelectric (multi-part)
Practice Checklist
Before the exam, you should be able to:
- [ ] Solve Case 1 photoelectric: Find $h$ and $\phi$ from two data pairs
- [ ] Solve Case 2 photoelectric: Find $\phi$ from $E$ and $K_{max}$
- [ ] Solve Case 3 photoelectric: Find $\phi$ from $f_0$
- [ ] Calculate de Broglie wavelength from KE (convert eV to J!)
- [ ] Calculate minimum $\Delta p$ from given $\Delta x$
- [ ] Calculate photon momentum from wavelength or energy
- [ ] Apply Gauss's Law to line charge, plane, and parallel plates
- [ ] Find electric field inside/outside conductors
- [ ] Calculate potential from multiple point charges
Related Resources
- FAD1022 Lecture 45 — Photon Momentum, Compton Effect, de-Broglie Waves & Heisenberg Uncertainty
- FAD1022 L4 — Electric Flux and Gauss Law
- FAD1022 L5 — Electric Flux and Gauss Law (continued)
- FAD1022 Tutorial 15 — Modern Physics (Student Version) — EXAM QUESTIONS HERE
- Photoelectric Effect — Worked Examples — 3 CASES EXPLAINED
- Rapid-Fire Drill Pack — Modern Physics Wave-Particle Duality — 36 practice problems
- Concept: Gauss's Law
- Concept: Electric Potential
#priority #exam-scope #final-exam #fad1022