Magnetic and electric fields

Magnetic and electric fields

1. Magnectic Fields

   • The area around a magnet where iron experiences a force
   • The magnectic field around a maganet is the same as a field around line coil, but inside the coil it goes from S to N
   • Right hand rule: thumb north, fingers curl in direction

2. The motor effect

   • More current, more coils, and a stronger magnet makes the wire move faster/further
   • A motor works as the two wires are forced in opposite directions causing a circular motion, they continue to be forced in opposite directions as the wires change where they are connected to the circuit because the split rings change sides

3. Magnetic flux density

   • The size of the force on the wave depends on three things; magnetic strength, current in the wire, and length of wire in the field
   • F = BIL

4. Electromagnetic induction

   • Can reverse the current in the wire when; wire is moved in the opposite direction, when the field is reversed, size of current is increased by; increasing speed, increasing magnet strength.
   • Wire placed through the magnetic field gives a current
   • Generating electricity right hand rule
   • When the south pole goes into the coil of wire induced current is produced in the coil
   • The direction of the current produces a magnetic field to stop the magnet from moving
   • Lenz's law: The induced E.M.F is always in such a direction as to oppose the charge that created it
     • F = Bqvsin

5. Electric Fields

   • Electric fields strength = E (v/m) = F/Q
   • Coulomb's law
     • f =Q1Q2/4π Ɛ0r^2
       • Eo = permitivity of free space r = distance between charges

6. Electric Field Strength

   • E= f/Q E + kQ/r^2

7. Electric potential

   • Defined as the amount of electric potential energy a point charge would have at a certain point, also the energy needed to move a unit charge from infinity to a point
   • v = hQ/r

8. Euipotential

   • is a line of constant electric potential
   • The potential differenence is the work done in transferring a unit positive charge from one point to another
   • Work done W = Qv

9. Magnetic flux

   • The amount of flux that passes though a given area
   • MF = MFD x area
     • Φ = NBSin0A
   • For a coil of N turns the total flux is NΦ
   • Faraday's law: The induced EMF for a magnet is a coil directly proportional to the rate of change of the flux linkage

10. Capacitors

    • Energy stored is the area under a graph