Key Terms
All magnets have two poles
North and south. North poles point toward Earth's geographic north; south poles point away.
FIELD LINE RULES (all four are testable)
1. Field direction is tangent to the line at every point; a compass needle points along it.
FORMULA
F = BIL sin(theta)
Smaller unit
1 Gauss (G) = 1 x 10^-4 T Earth's surface field: approximately 5 x 10^-5 T = 0.5 G Strong permanent magnets: near 2 T
Superconducting electromagnets
10 T or more
If velocity is not fully perpendicular to B
The parallel component is unaffected (no force on it); the perpendicular component creates circular motion. Combined res
Direction
RIGHT HAND RULE 2 (RHR-2): Point thumb in direction of current. Fingers curl in direction of B field loops.
Force per unit length
F/L = BI sin(theta)
MAXIMUM TORQUE
When theta = 90 degrees (loop plane parallel to B field). ZERO TORQUE: when theta = 0 degrees (loop plane perpendicular
MOTORS
Use this principle. Electrical energy converts to mechanical (rotational) work.
PINCH EFFECT
In an electric arc, parallel currents attract and squeeze the arc into a smaller cross-section. Can burn out large circu
CATHODE RAY TUBES (CRTs)
Electron guns accelerate electrons; magnetic coils steer them to specific screen locations. Two perpendicular coil pairs