Electrodynamics - SAGS Definitions

SAGS Definition of: Magnetic field

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 strength is B and the unit is the Tesla (T).

SAGS Definition of: Right hand rule

When you hold a current carrying conductor in your right hand so that your thumb points in the direction of conventional current, your fingers will curl in the direction of the magnetic field.

SAGS Definition of: Solenoid rule (Right hand thumb rule)

When you hold a solenoid in your right hand so that your fingers curl in the direction of conventional current, your thumb will point in the direction of the north pole.

SAGS Definition of: Magnetic Flux Density (B)

A representation of the magnitude and direction of the magnetic field.

SAGS Definition of: Magnetic flux (Φ)

For a loop of area (A) the magnetic flux (Φ) passing through the loop in the presence of a uniform magnetic flux density (B) is defined as Φ = BA cosθ, where θ is the angle between the magnetic flux density (B) and the normal to the loop of area (A). (No calculations required)

SAGS Definition of: Magnetic flux linkage

The product of the number of turns on the coil and the flux through the coil (NΦ).

SAGS Definition of: Faraday's law

The emf induced in a coil is directly proportional to the rate of change of magnetic flux (flux linkage).

SAGS Definition of: 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.

SAGS Definition of: 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.

SAGS Definition of: AC

Alternating current. Current which reverses direction periodically.

SAGS Definition of: Commutator

A device that ensures that the direction of the current in a coil is reversed every half revolution.

SAGS Definition of: Conventional current

The rate of flow of positive charge from the positive terminal of the cell to the negative terminal.

SAGS Definition of: DC

Direct current. Current flowing in one direction only.

SAGS Definition of: Diode

A component that only allows current to flow in one direction.

SAGS Definition of: Bridge rectifier

A type of full-wave rectifier that uses four or more diodes in a bridge circuit configuration to efficiently convert alternating (AC) current to a direct (DC) current.

SAGS Definition of: Fleming’s Left Hand Motor Rule

Thumb = Force
Index / pointer finger = Magnetic field
Middle finger = Direction of current

SAGS Definition of: Fleming’s Right Hand Generator Rule

Thumb = Force
Index / pointer finger = Magnetic field
Middle finger = Direction of current