2-2-3
The ? concentrates and directs the magnetic field and makes transformers possible. Select one: a.iron core b.magnetic flux c.turns ratio d.wire coil
A. Iron core
Impedance is the combination of resistance and current. Select one: True False
False
Since transformers have no moving parts, their efficiency is always 100%. Select one: True False
False
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. Select one: True False
False
The primary coil of a transformer is always a high voltage winding. Select one: True False
False
A power plant transformer ? the voltage and ? the current on a transmission line. Select one: a.increases / increases b.increases / reduces c.reduces / increases d.reduces / reduces
b.increases / reduces
To obtain maximum induction, the coils must be ? and ? so the field is able to cut across the conductors of the other. Select one: a.parallel / at a right angle b.parallel / sufficiently close c.parallel / touching d.the same size / at a right angle
b.parallel / sufficiently close
A transformer may be either a ? or a ? , depending on its use. Select one: a.conventional / CSP b.distribution / residential c.step up / step down d.transmission / distribution
c.step up / step down
Ohm's Law cannot be used directly on AC circuits because ? . Select one: a.of alternating current b.of alternating voltage c.of line loss and heat created by current flow d.reactance and resistance oppose current flow
d.reactance and resistance oppose current flow
AC at 60 hertz per second increases and decreases in value ? times per second. Select one: a.60 b.120 c.180 d.200
B. 120
The lines of force must be ? in order to induce a voltage and cause a current to flow in the circuit. Select one: a.expanding b.in motion c.sufficiently close d.sufficiently strong
B. In motion
Adding more turns to a coil ? the magnetic effect. Select one: a.decreases b.increases c.slows down d.speeds up
B. Increases
The amount of current flowing and the ? are two of the three things that govern the strength of a transformer's electromagnetic field. Select one: a.load that is to be connected b.number of turns in the winding c.primary voltage it is connected to d.the secondary voltage required
B. Number of turns in the winding
Using Watt's Law, when reducing voltage through a transformer, the ? to supply the load. Select one: a.current is limited b.current will decrease c.current will increase d.smaller wire can be used
C. Current will increase
All transformer connections, whether single or 3-phase, are based on the voltage and current rules for ? and ? circuits. Select one: a.AC / DC b.resistance / reactance c.series / parallel d.transformers / resistance
C. Series / Parallel
As the magnetic field in the primary coil increases in strength, the current in the secondary increases. Select one: True False
True
In order for current to flow, the conductor must be a closed circuit. Select one: True False
True
Laminating an iron core directs the maximum amount of magnetic flux lengthways in the iron core. Select one: True False
True
The current and the magnetic field in an AC circuit reverse direction twice in each cycle. Select one: True False
True
The kilovolt-amperes being drawn off of a transformer can be found by multiplying secondary voltage times secondary amperage and dividing the result by one thousand. Select one: True False
True
The magnetic field surrounding a coil rises and falls in unison with the current. Select one: True False
True
The primary of a transformer designates the winding that is supplied with electricity. Select one: True False
True
