amazon.co.ukP2: Waves, Optics and Superposition
Progressive and stationary waves, Young's double-slit experiment, diffraction gratings, refractive index, total internal reflection.
📋 Key Definitions and Core Concepts
Superposition Principle: When two waves meet, the resultant displacement is the vector sum of individual displacements.
Coherence: Waves with constant phase difference and identical frequency/wavelength.
🔍 Key Principles & Specification Requirements
- Double slit fringe spacing: w = λD / s (fringe separation w, slit spacing s, screen distance D).
- Diffraction grating equation: d sin θ = nλ (d = grating spacing = 1/N lines per metre).
- Snell's law: n₁ sin θ₁ = n₂ sin θ₂; Critical angle sin θ_c = n₂ / n₁ (for n₁ > n₂).
💡 Worked Example Question
Exam-Style Question
Question:
Laser light (λ = 632.8 nm) is incident on a grating with 300 lines/mm. Find angle of 2nd order maximum.
Model Solution & Mark Scheme:
d = 1 / (300 × 10³) = 3.333 × 10⁻⁶ m. d sin θ = nλ => sin θ = (2 × 632.8 × 10⁻⁹) / (3.333 × 10⁻⁶) = 0.3797. θ = arcsin(0.3797) = 22.3°.
❓ Practice Questions & Mark Schemes
Q1: Explain how stationary waves are formed on a stretched string.
Show Model Answer
Answer: Two identical progressive waves travelling in opposite directions with equal frequency and amplitude superpose, creating nodes (zero displacement) and antinodes (maximum displacement).
Q2: Calculate critical angle for glass (n = 1.52) to air (n = 1.00).
Show Model Answer
Answer: sin θ_c = 1.00 / 1.52 = 0.6579 => θ_c = 41.1°.
🎬 Video Resources
- Waves, Optics and Superposition - Overview -- YouTube Search
- Waves, Optics and Superposition - Exam Questions -- YouTube Search
📄 Past Papers & Exam Resources
- AQA A-Level - Past Papers -- AQA
- Edexcel A-Level - Past Papers -- Edexcel
- OCR A-Level - Past Papers -- OCR
🔗 Further Reading & Resources
- Physics & Maths Tutor -- Free notes, worksheets, and past paper questions by topic
- Dr Frost Maths -- Free resources, slides, and interactive questions
- BBC Bitesize -- BBC Bitesize revision resources