ElectroMagnetism

1. Force on a current-carrying conductor

1.1. magnitude: F=BILsin θ

1.2. direction: FLHR

1.3. Current balance experiment

1.3.1. to measure: magnetic flux density or magnetic field strength, B

1.3.1.1. the force exerted per unit length per unit current on a conductor placed perpendicularly to the magnetic field

1.3.1.2. units: Tesla(T)

2. Magnetic Fields due to currents

2.1. Permeability of free space µ0 = 4π×10−7 Hm-1

2.2. Right hand grip rule

2.2.1. Long straight wire

2.2.2. Flat circular coil

2.2.3. long solenoid

3. Force on a moving charge

3.1. magnitude => F=BQvsinθ

3.2. direction FLHR

3.3. Analyse the direction of a moving charge by uniform electric field and uniform magnetic field

3.3.1. Velocity selector: Fe=Fa qE=Bqv v=E/B

4. Force between current-carrying conductors

4.1. Anaylse the forces due to magnetic fields of current-carrrying conductors

4.1.1. Perpendicular wires

4.1.1.1. No force experienced

4.1.2. Parallel Wires

4.1.2.1. Different direction: repel as the direction of magnetic field in between the two wires is the same and will be added together and repel the two wires

4.1.2.2. Same direction: attract as the direction of magnetic field in between the two wires is opposite to each other and cancels out