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Electromagnetism Formula

What is Magnetic Flux?

Magnetic flux measures how much magnetic field passes through a surface.

Formula: \Phi_B = BA\cos\theta

Plain-English Meaning

Magnetic flux measures how much magnetic field passes through a surface.

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

Deeper Explanation

Magnetic flux measures how much magnetic field passes through a surface.

Worked Example

Problem: B = 0.4 T passes through a 0.05 m² loop at 30° to the normal. Find Φ_B.

  • Φ_B = BA cosθ = 0.4 × 0.05 × cos30°
  • Φ_B = 0.02 × 0.866 = 0.0173 Wb

Result: Φ_B ≈ 0.0173 Wb

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.