Magnetism Flashcards
Magnetic Field
Any region of space where magnetic forces can be felt. The direction of the magnetic field at a point is the direction of the force on a North Pole if it were placed at the point
Right Hand Grip Rule
Grasp a conductor with your right hand, with the thumb pointing in the direction of current. The fingers give the direction of the magnetic field
Fleming’s Left Hand Rule
If the thumb, first finger and second finger of the left hand are held at right angles, with the first finger pointed in the direction of the magnetic field and the second finger pointing in the direction of the current, the thumb points in the direction of the force
Magnetic Flux Density
Point in a magnetic field is a vector whose magnitude is equal to the force that would be experienced by a conductor of length 1m carrying a current of 1A at right angles to the field at that point and whose direction is the direction of the force on a North Pole placed at that point
Ampere
Constant current which, if maintained in two straight parallel conductors or infinite length, of negligible cross section and placed 1m apart in a vacuum would produce a force on each conductor of 2x10^-7 Newtons per metre of length
Electromagnetic Induction
Whenever the magnetic field passing through a coil changes an EMF appears in the coil
Faraday’s Law of Electromagnetic Induction
The size of the induced EMF is directly proportional to the rate of change of flux.
Lenz’s Law
States that the direction of an induced current is always such to oppose the change producing it
Electric Generator
Device that converts mechanical energy to electrical energy
Mutual Induction
If a changing magnetic field in one coil causes an induced EMF to appear in a nearby coil there is said to be mutual induction between the two coils
Self-Induction
Whenever the current passing through a coil changes, the magnetic field surrounding the coil changes. This changing magnetic field induces an emf in the coil that opposes the changing current.
Transformer
Device used to change the value of an alternating voltage
