The AQA A-level Physics Paper 3B (November 2021), Option E (Electronics), focuses on key electronic principles and circuit analysis. Topics include MOSFET characteristics, logic gate operations, and photodiode applications. The paper emphasizes Boolean algebra, circuit design for alarm systems, and calculations involving responsivity and amplification in photodetectors. It explores counter circuits, oscillators, and their applications in digital electronics. Transmission pathways for electromagnetic waves are analyzed for various frequency ranges in communication systems. Keywords: AQA Physics, electronics, MOSFET, logic gates, photodiode, Boolean algebra, counters, communication systems, electromagnetic spectrum.