Sections
Glossary
Glossary
- back emf
- the emf generated by a running motor, because it consists of a coil turning in a magnetic field; it opposes the voltage powering the motor
- capacitive reactance
- the opposition of a capacitor to a change in current; calculated by
- characteristic time constant
- denoted by of a particular series RL circuit is calculated by where is the inductance and is the resistance
- eddy current
- a current loop in a conductor caused by motional emf
- electric generator
- a device for converting mechanical work into electric energy; it induces an emf by rotating a coil in a magnetic field
- electromagnetic induction
- the process of inducing an emf (voltage) with a change in magnetic flux
- emf induced in a generator coil
- where is the area of an -turn coil rotated at a constant angular velocity in a uniform magnetic field over a period of time
- energy stored in an inductor
- self-explanatory; calculated by
- Faraday’s law of induction
- the means of calculating the emf in a coil due to changing magnetic flux, given by
- henry
- the unit of inductance;
- impedance
- the AC analogue to resistance in a DC circuit; it is the combined effect of resistance, inductive reactance, and capacitive reactance in the form
- inductance
- a property of a device describing how efficient it is at inducing emf in another device
- induction
- (magnetic induction) the creation of emfs and hence currents by magnetic fields
- inductive reactance
- the opposition of an inductor to a change in current; calculated by
- inductor
- a device that exhibits significant self-inductance
- Lenz’s law
- the minus sign in Faraday’s law, signifying that the emf induced in a coil opposes the change in magnetic flux
- magnetic damping
- the drag produced by eddy currents
- magnetic flux
- the amount of magnetic field going through a particular area, calculated with where is the magnetic field strength over an area at an angle with the perpendicular to the area
- mutual inductance
- how effective a pair of devices are at inducing emfs in each other
- peak emf
- phase angle
- denoted by the amount by which the voltage and current are out of phase with each other in a circuit
- power factor
- the amount by which the power delivered in the circuit is less than the theoretical maximum of the circuit due to voltage and current being out of phase; calculated by
- resonant frequency
- the frequency at which the impedance in a circuit is at a minimum, and also the frequency at which the circuit would oscillate if not driven by a voltage source; calculated by
- self-inductance
- how effective a device is at inducing emf in itself
- shock hazard
- the term for electrical hazards due to current passing through a human
- step-down transformer
- a transformer that decreases voltage
- step-up transformer
- a transformer that increases voltage
- thermal hazard
- the term for electrical hazards due to overheating
- three-wire system
- the wiring system used at present for safety reasons, with live, neutral, and ground wires
- transformer
- a device that transforms voltages from one value to another using induction
- transformer equation
- the equation showing that the ratio of the secondary to primary voltages in a transformer equals the ratio of the number of loops in their coils;