MDCAT Electromagnetism 2026 — Magnetic Force, Induction & Lenz's Law

Core Formulas

• Force on wire — F = BIL sinθ
• Force on moving charge — F = qvB sinθ
• Magnetic field of long wire — B = μ₀I/(2πr)
• Induced EMF — ε = −dφ/dt (Faraday); φ = BA cosθ
• Motional EMF — ε = BvL

Lenz's Law

The induced current opposes the change in flux that caused it (energy conservation).

Right-Hand Rules

• Thumb = current; fingers curl = magnetic field direction (long wire).
• For F = qvB: fingers point in v, curl toward B, thumb gives F (positive charge).

Pair with Current Electricity and past papers.