Units
| Quantity | SI unit | CGS unit | Conversion |
|---|---|---|---|
| Magnetic flux density B | Tesla (T) | Gauss (G) | 1 T = 10 000 G |
| Magnetic field strength H | A/m | Oersted (Oe) | 1 Oe = 79.577 A/m |
| Magnetic flux Φ | Weber (Wb) | Maxwell (Mx) | 1 Wb = 10⁸ Mx |
| Permeability μ | H/m | — | μ₀ = 4π × 10⁻⁷ H/m |
Typical field strengths
| Source | Field |
|---|---|
| Earth's magnetic field | 25–65 µT (0.25–0.65 G) |
| Refrigerator magnet | ~5 mT (50 G) |
| Strong neodymium magnet (surface) | 0.5–1.5 T (5–15 kG) |
| MRI (clinical) | 1.5 – 3 T |
| Strongest continuous lab magnet | 45 T |
| Pulsed lab magnet | hundreds of T |
| Neutron star surface | 10⁸ – 10¹¹ T |
Key relations
| B in free space | B = μ₀ H |
|---|---|
| Magnetic flux | Φ = B · A (perpendicular area) |
| EMF (Faraday) | ε = −dΦ/dt |
| Force on moving charge | F = qv × B |
| Force on wire | F = IL × B |
Was this article helpful?