4.1 Magnetic Field

• a region around magnet where magnetic force can be experienced.
• 2 poles: North(N) & South (S)
• (N-N or S-S) = repel.
• (N-S) = attract

Magnetic field lines:

• the lines that leave north pole and enter south pole.
• can be represented by crosses or dotted circles.
• do not intersect one another.
  
  

cross - magnetic field enter
dot circle - magnetic field leave

Magnetic flux density, B

• the magnetic flux per unit area across an area at right angles to the magnetic field.
• vector quantity.
• direction follows the direction of magnetic field.

• unit: Tesla (T) / weber per metre squared.

  
  
  

  

4.2 Magnetic Field Produced By Current Carrying Conductor

When current flows in conductor, magnetic field produced.
Direction of magnetic field around wire/coil determined by right hand drip rule.

4.3 Magnetic Force On Moving Charged Particles in Uniform Magnetic Field

Magnetic Force

• A stationary electric charge in a magnetic field will not experienced a magnetic force.

• If charge move with velocity, magnetic field will experienced magnetic force.

  
  
  

  

4.5 Magnetic Force between Two Parallel Current Carrying Conductor

Force per unit length

Two straight parallel conductors carrying currents:

4.6 Torque On a Coil

T = NIAB cos (teta)

4.7 Motion of Charged Particles in Magnetic Field & Electric Field

• The charged particle will experiences the electric force is downward with magnitude & the magnetic force is upwards with magnitude qvB.

  
  

• If particle travels in a straight line with constant velocity. Hence, the electric & magnetic forces are equal in magnitude.

  
  
  

Fb = Fe
qvB sin(90) = qE ---> v = E/B

Velocity Selector

When charged particle entering the region consists magnetic field only, the particle will make a semicircular path of radius.