How do capacitors work, and what is their role in storing electrical energy in a circuit?

A capacitor stores electrical energy by accumulating opposite charges on two parallel conducting plates separated by an insulator (dielectric), creating a potential difference.

Step-by-Step Solution:
When connected to a voltage source, electrons flow to one plate (negative) while electrons are removed from the other (positive)
The charge stored (Q) relates to capacitance (C) and voltage (V) by Q = CV
Energy stored = ½CV² = ½QV = ½Q²/C
During discharge, stored energy releases as electrons flow back through the circuit until plates neutralize

Key Mistake to Avoid: Students often confuse capacitors with batteries - remember capacitors store charge through electric fields, not chemical reactions, and discharge much more rapidly.


AQA requires quantitative analysis of charging/discharging
OCR emphasizes energy storage calculations
Edexcel includes RC circuits applications

Quick Tip: Draw parallel plate diagrams with charge distribution to visualize the storage mechanism - this helps solve energy calculations in exams.