Magnetic Fields
The dynamics of magnetic dipole interactions and fields.
Magnetic fields exert forces on moving charges and magnetic dipoles. Magnetic poles always exist as dipoles (North and South).
This unit covers magnetic fields of permanent bar magnets, magnetic field lines, and the magnetic force acting on moving charges.
Key Takeaways
- •Magnetic fields are generated by moving charges or intrinsic spin dipoles.
- •Like magnetic poles repel; opposite poles attract.
- •There are no isolated magnetic monopoles.
Core Concepts & Definitions
1Lorentz Force on Charges
A magnetic field (B) exerts no force on static charges. It only exerts a force on charges moving with velocity (v).
•F = q * v * B * sin(θ), where θ is the angle between velocity and field.
•Force direction is perpendicular to both velocity and field, determined by the Right-Hand Rule.
2Magnetic Field Lines
Visual representations of the magnetic field vector.
•Lines emerge from the North pole and enter the South pole.
•Density of lines represents field strength.
Quick Revision Notes
- •The unit of magnetic field strength (B) is the Tesla (T).
- •Always use the Left-Hand Rule for negative charges (or reverse the result of the Right-Hand Rule).