6c) Electromagnetism

Magnetic fields in current-carrying wire:

• an electric current in a material produces a magnetic field around it 
• the larger the electric current, the stronger the magnetic field 
• the direction of the magnetic field depends on the direction of the current 

Paper Two-

Straight wire, Flat circular coil and Solenoid:

The magnetic field around a straight wire is circular:

The magnetic field around a flat circular coil ellipses (egg-shaped):

The magnetic field around a solenoid  is electromagnet: 

If something with a charge is moving across a magnetic field it will 

experience a force from the field, unless it's parallel. 

D.C. Electric Motor (simple):

• wire in magnetic field 
• force turns a 'split ring communicator' ---> charge goes from brushes in wires 

      Four factors

1. more current 
2. more turns on coil 
3. stronger magnetic field 
4. soft iron core 

Loudspeaker:

• force pushes current away from field, pushes core which makes sound ---> cone vibrates 

The left hand rule:

Helps to figure out the thrust/motion, field and current of the wire to then work out which way the force is acting.

Wire in magnetic field increase (<) current = more force on wire 

Wire in magnetic field increase (<) strength = more force on wire