Complete AS Level Physics lesson: Young's double-slit interference. CIE style worked examples.

A full, ready-to-teach 13-slide Power point lesson on Two-Source Interference and Young’s Double-Slit Experiment, designed for AS Level / Cambridge International (CIE) Physics, topic 8.3.

What’s included:

• Starter recall task on stationary waves (nodes/antinodes)
• Clear learning objectives and “I Can” success criteria
• The four conditions for observable interference fringes (coherence, same frequency, similar amplitude, same plane of polarisation)
• Constructive vs destructive interference explained through path difference
• Derivation and explanation of the fringe spacing formula λ = ax/D
• A fully worked CIE board-style numerical example (fringe spacing + counting fringes)
• Group challenge task (predict/explain, calculate, analyse — differentiated for pair/group work)
• Quick-fire mini plenary with model answers
• Tiered Core/Extension/Mastery success criteria for differentiation
• Full plenary with self-assessment checklist and exit ticket
• Embedded video link to a double-slit demonstration

How to use it:
Ideal for a single 60-75 minute AS/A Level lesson, or split across two shorter periods. Works well for CIE, but conditions and formula transfer directly to Edexcel/AQA/OCR A-Level and IB Physics interference topics too, with minor tweaks to exam-board wording.

Suitable for: AS Level Physics, A-Level Physics (Year 12), IGCSE Extension/Further Physics extension work, IB DP Physics SL/HL.