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Electromagnetism Formula

What is Magnetic Force on a Moving Charge?

A charge moving through a magnetic field experiences a force perpendicular to both its velocity and the field.

Formula: F = qvB\sin\theta

Plain-English Meaning

A charge moving through a magnetic field experiences a force perpendicular to both its velocity and the field.

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

Deeper Explanation

A charge moving through a magnetic field experiences a force perpendicular to both its velocity and the field.

Worked Example

Problem: A proton (q = 1.6×10⁻¹⁹ C) moves at 2×10⁶ m/s perpendicular to B = 0.5 T. Find the force.

  • F = qvB sinθ = 1.6×10⁻¹⁹ × 2×10⁶ × 0.5 × sin90°
  • F = 1.6×10⁻¹³ N

Result: F = 1.6×10⁻¹³ N

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.