intro to transformers Flashcards
The current and the magnetic field in an AC circuit reverse direction twice in each cycle.
true
Ohm’s Law cannot be used directly on AC circuits because ?
reactance and resistance oppose current flow.
Impedance is the combination of resistance and current.
false
All transformer connections, whether single or 3-phase, are based on the voltage and current rules for ? and ? circuits.
series / parallel
AC at 60 hertz per second increases and decreases in value ? times per second.
120
The magnetic field surrounding a coil rises and falls in unison with the current.
true
As the magnetic field in the primary coil increases in strength, the current in the secondary increases.
true
The lines of force must be ? in order to induce a voltage and cause a current to flow in the circuit.
in motion
The ? concentrates and directs the magnetic field and makes transformers possible.
iron core
Laminating an iron core directs the maximum amount of magnetic flux lengthways in the iron core.
true
The ease with which the core can be magnetized is not one of the three things that govern the strength of a transformer’s electromagnetic field.
false
The amount of current flowing and the ? are two of the three things that govern the strength of a transformer’s electromagnetic field.
number of turns in the winding
The primary of a transformer designates the winding that is supplied with electricity.
true
The primary coil of a transformer is always a high voltage winding.
false
A transformer may be either a ? or a ? , depending on its use.
step up / step down
