Electrodynamics Flashcards
Faraday’s law
The emf induced is directly proportional to the rate of change of magnetic flux (flux linkage).
AC
Alternating current. Current which reverses direction periodically.
Commutator
A device which ensures that the direction of the current in a coil is reversed every half revolution.
Conventional current
The rate of flow of positive charge from the positive terminal of the cell to the negative terminal.
DC
Direct current. Current flowing in one direction only.
Electromagnetic induction
Occurs when a current is induced in a closed conducting loop when there is a change in the magnetic flux passing through the surface area of the conducting loop.
Induced emf
The total amount of electrical energy supplied per unit positive charge.
Magnetic fields
Produced by magnets or by moving electrical charges. Magnetic field lines are drawn to represent the direction of the magnetic field at a point. The symbol for magnetic field is B and its unit is the Tesla (T).
Magnetic flux density
A representation of the magnitude and direction of the magnetic field.
Magnetic flux
For a loop of area (A) in the presence of a uniform magnetic flux density (B), the magnetic flux (Ф) passing through the loop is defined as Ф = BA cos®, where 0 is the angle between the magnetic flux density (B) and the normal to the loop of the area (A).
Magnetic flux linkage
The product of the number of turns on a coil and the flux through a coil (N).
Lenz’s law
The induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux.
Diode
A component that only allows current to flow in one direction.
Generator
A device which converts mechanical energy into electrical energy.
Motor
A device which converts electrical energy into mechanical energy.
