IEM Flashcards
a device that is used to change the magnitude of electric current and potential into higher and lower values.
Transformer
Transformer applies the principle of
mutual induction
Transformer will operate only with a
changing electric current (AC)
Usually composed of wires wrapped around in an iron core and consists of
primary and secondary coils
The change in the voltage is ______ to the ratio of the number of turns (windings) in the secondary coil (Ns) to the number of turns in the primary coil (Np).
directly proportional (tranformer law)
The change in current across a transformer is in the ______ from the voltage change but in the ______.
opposite direction
same proportion
transformer with a turns ratio greater than 1
Step up transformer
Increases the voltage but decreases the current.
Step up tranformer
a transformer with turns ratio less than 1
Step down transformer
Decreases the voltage but increases the current.
Step down transformer
is made from a single primary winding wrapped around a laminated magnetic core, and operates on the principle of self-induction.
Autotransformer
tapped at various points along its length to provide a percentage of the primary voltage supply across its secondary load.
Single winding
is a device that stores electric charges producing a potential difference (static voltage) across its plates, much like a small rechargeable battery.
Capacitor
consists of two or more parallel conductive (metal) plates that are electrically separated either by air or insulating material.
Capacitor
The insulating material between plates is called
dielectric
is an electrical device which converts an alternating current (AC) into a direct current (DC) by allowing the current to flow through it in only one direction.
Rectifier
the process of converting AC to DC.
Rectification
a pulsating DC and not a smooth DC.
Output DC
a pulsating DC and not a smooth DC.
Diodes
Types of Rectification
- Half-wave rectification
- Full-wave rectification
Uses one or two diodes that allow only half of the AC cycle to pass, while the other half is blocked.
Half wave rectification
Uses several diodes that allow both the positive and negative cycle of the AC wave to pass.
Full wave rectification
an electrical instrument that is used to control current by varying the resistance.
Rheostat
able to vary the resistance in a circuit without interruption.
Rheostats
a device that opens a circuit as soon as current climbs to unsafe levels.
Circuit breaker
consists of a simple switch, connected to electromagnet.
The basic circuit breaker
a backup pathway that provides an alternate route for electrical current to flow back into ground in the case of a problem in the wiring system.
Grounding system
