Electrotechnology Flashcards
What can be used so that one side of the loop is always connected to the same side of the external circuit?
a. An armature
b. Slip rings
c. A commutator
d. Brushes
b. Slip rings
Apparent power is the
Select one:
a. kW of power consumed
b. VA supplied to a reactive AC circuit
c. Power due to resistance in a circuit
d. Power recorded by a kWh meter.
b. VA supplied to a reactive AC circuit
When using the Left Hand Rule for Motors, the index finger represents:
Select one:
a. Magnetic flux direction, for generators
b. Conductor motion direction, for motors
c. Flux direction, for motors
d. Direction of current flow, for motors.
c. Flux direction, for motors
Transformers require:
Select one:
a. More maintenance than other electric machinery
b. Less maintenance than most other electric machinery
c. Inspection every three years
d. Inspection every month
b. Less maintenance than most other electric machinery
If the secondary circuit of a current transformer is opened while the primary is energized, what will happen to the secondary voltage?
a. Increase and then decrease
b. Increase
c. Decrease
d. Remain same
b. Increase
If a conductor is held stationary and a magnetic field is moved across it, it behaves according to
Select one:
a. Motor action
b. Electromagnetism
c. Generator action
d. Transformer action
c. Generator action
Which formula expresses the relation between the voltage (E) in each winding of a simple transformer and the number of turns (N) in each winding?
a. Ep/Np=Es/Ns
b. Ep/Ns=Es/Np
c. Es/Ep=Ns/Np
d. Ep/Es=Np/Ns
d. Ep/Es=Np/Ns
Copper losses in a transformer are reduced by:
Select one:
a. Using iron core laminations instead of copper
b. Using larger diameter wire
c. Reducing the primary voltage
d. Increasing the secondary voltage
b. Using larger diameter wire
The stator of an alternator is built of _____ mounted in a frame.
Select one:
a. Copper alloys
b. Laminated steel sheets
c. Carbon ring
d. Armature conductors
e. Non-metallic materials
b. Laminated steel sheets
When magnetic flux produced by one coil induces an EMF in a second coil, it is called:
Select one:
a. Self inductance
b. Electromagnetic induction
c. Mutual inductance
d. Inductive reactance
c. Mutual inductance
A rheostat is also known as
Select one:
a. a voltage regulator
b. an automatic resistor
c. a variable resistor
d. an exciter
c. a variable resistor
The rotating field of an alternator is produced by applying _________ to the rotor.
Select one:
a. AC power
b. Magnetic flux
c. DC power
d. Apparent power
c. DC power
The right hand rule for generators is used to:
Select one:
a. Indicate the speed of a rotor
b. Determine direction of induced current flow
c. Determine the frequency of an alternator
d. Determine magnetic flux rotation
b. Determine direction of induced current flow
Synchronous motors have construction that is identical to:
Select one:
a. DC series motors
b. DC shunt motors
c. AC induction motors
d. Alternators
d. Alternators
Single-phase transformers:
Select one:
a. Use two common forms of construction known as the core type and the shell type.
b. High voltage coil is nearest the iron core.
c. Use two common forms of construction known as the internal type and the external type.
d. Are very low in efficiency.
a. Use two common forms of construction known as the core type and the shell type.
