Magnetic Effects of Electric Current
Rules, Field Patterns & Mechanisms
Used to find the direction of the magnetic field around a straight current-carrying conductor.
↔ Swipe to view rule logicThumb: Direction of Current ($I$)
Fingers (Wrapped): Direction of Magnetic Field ($B$)
Field Strength ($B$): $$B \propto I \quad \text{and} \quad B \propto \frac{1}{r}$$
A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder.
Property: Field inside a long solenoid is uniform and parallel.
Strength ($B$): Depends on current ($I$) and number of turns per unit length ($n$).
$$\text{Behavior} \approx \text{Bar Magnet}$$
Used to find the direction of the force (motion) acting on a conductor placed in a magnetic field.
Thumb: Motion / Force ($F$)
Forefinger: Magnetic Field ($B$)
Middle Finger: Current ($I$)
$$\text{Remember as ‘FBI’ (Force, Field, Current)}$$
The process by which a changing magnetic field in a conductor induces a current in another conductor.
Fleming’s Right Hand Rule (Generator):
• Thumb: Movement of Conductor
• Forefinger: Magnetic Field
• Middle Finger: Induced Current
Standard wiring parameters used in household electrical systems.
Potential Difference: $220 \text{ V}$
Frequency: $50 \text{ Hz}$
Wire Color Code:
• Live (L): Red | Neutral (N): Black | Earth (E): Green