Electrodynamics Flashcards
Define magnetic field
It is 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 is B and the unit is the Tesla ( T )
Define magnetic flux density
It is a representation of the magnitude and direction of the magnetic field.
Define 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 cosθ, where θ is the angle between the magnetic flux density (B) and the normal to the loop of the area (A). (No calculations required)
Define magnetic flux linkage
The product of the number of turns on the coil and the flux through the coil. (NФ)
Define faraday’s law
The emf induced in a coil is directly proportional to the rate of change of magnetic flux. (flux linkage)
Define 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.
Define 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
Define alternating current ( AC )
Current which reverses direction periodically.
Define commutator
Is a device that ensures that the direction of the current in a coil is reversed every
half revolution.
Define conventional current
Is the rate of flow of positive charge from the positive terminal of the cell to the negative terminal.
Define direct current ( DC )
Current flowing in one direction only.
Define emf
The electrical energy supplied per unit charge delivered to the circuit.
Define diode
A component that only allows current to flow in one direction.
