Magnetic fields

• A current flowing through a wire produces its own magnetic field
• The motor effect is when a wire with current is in another magnetic field and experiences a force
• The equation for the force (F) on the wire is F = BIL, where I is current in amps, L is length of the wire in the magnetic field, and B is the magnetic flux density (measured in Tesla)
• The alternative unit for magnetic flux density is Newtons per amp per meter
• The equation only works if the current and magnetic field lines are perpendicular to each other
• If the wire is parallel to the field lines, it will experience no force
• Fleming's left-hand rule is used to determine the direction of the force on the wire
• A cyclotron uses F = Bqv to produce high-energy particles like protons for medical therapy
• In a mass spectrometer, particles separate out according to their masses when exposed to a magnetic field
• Flux is the amount of magnetism an area is exposed to, symbolized by F and measured in Webers (Wb)
• Flux density is equal to flux over area, measured in Tesla or Newtons per amp per meter squared
• To calculate total flux linkage in a coil, multiply flux by the number of turns in the coil (n)
• EMF induced in a wire is proportional to the rate of change of flux linkage, according to Faraday's law
• The direction of the induced current opposes the change that caused it, known as Lenz's law
• Transformers change the voltage of electricity transmitted through overhead cables by altering the turns ratio of coils
• In an ideal transformer, power in equals power out, making it 100% efficient
• Lenz's law also applies to motors, where back EMF opposes the driving EMF to regulate motor speed and prevent burnout