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Electromagnetism Formula

What is Energy Stored in a Capacitor?

A charged capacitor stores energy in its electric field; this energy equals ½CV².

Formula: U = \frac{1}{2}CV^2

Plain-English Meaning

A charged capacitor stores energy in its electric field; this energy equals ½CV².

Keep charge, field, potential, and current distinct. That single habit fixes a large fraction of electromagnetism errors.

Deeper Explanation

A charged capacitor stores energy in its electric field; this energy equals ½CV².

Worked Example

Problem: A 100 μF capacitor is charged to 50 V. How much energy is stored?

  • U = ½CV² = ½ × 100×10⁻⁶ × 50²
  • U = ½ × 10⁻⁴ × 2500 = 0.125 J

Result: 0.125 J

At A Glance

Category: Electromagnetism

Levels covered:

Best use: Start with the formula meaning, then move to the worked example and quiz so the equation turns into a tool instead of a memorised line.