A-08: Basic Concepts In Electrotechnology

Question 1

Which of the following affects the electromotive force developed by a DC generator?

A. Acceleration rate at which the conductors cut the magnetic lines of force
B. The diameter of the conductors
C. The type of conductors cutting the magnetic lines of force
D. The strength of the stationary field

Answer 1

D. The strength of the stationary field

Question 2

Iron losses which occur in a transformer are caused by eddy currents, hysteresis and:

A. Cooling losses
B. Flux leakage
C. Capacitive losses
D. Inductive losses

Answer 2

B. Flux leakage

Question 3

An Ammeter must ______ to the electrical circuit.

A. Offer low resistance
B. Offer no resistance
C. Offer a high resistance
D. Apply a voltage

Answer 3

A. Offer low resistance

Question 4

Because of environmental concerns, it is no longer permissible to add _______ to transformer oil.

A. Anti-foaming substances
B. Polyhlorinated biphenyls
C. Freon
D. Organic compounds

Answer 4

B. Polyhlorinated biphenyls

Question 5

The measurement of the total magnetic field that passes through an area is:

A. Known as the EMF
B. Controlled by varying the temperature
C. Called the magnetic flux
D. Determined by the north magnetic pole

Answer 5

C. Called the magnetic flux

Question 6

The voltage produced in each phase of a three phase generator is displaced by ______ electrical degrees from the other phases :

A. 120
B. 90
C. 60
D. 30

Answer 6

A. 120

Question 7

The maximum voltage generated by a single loop DC generator occurs, when the conductor is cutting the magnetic lines of force at an angle of:

A. 0 degrees
B. 45 degrees
C. 90 degrees
D. 120 degrees

Answer 7

C. 90 degrees

Question 8

The strength of the magnetic field produced in a shunt wound generator:

A. Is weak
B. Is fairly constant
C. Is regulated by an external AC supply
D. Increases with generator load

Answer 8

B. Is fairly constant

Question 9

The utility’s responsibility does not go beyond a customers

A. First branch line
B. First over current device
C. Primary transformer
D. Motor control center

Answer 9

B. First over current device

Question 10

What concept does Lenz’s law apply to?

A. AC electrical theory
B. Electrical energy
C. Electro-magnetic induction
D. The relationship between voltage, current, and resistance

Answer 10

C. Electro magnetic induction

Question 11

Which meter is used to test the quality of a conductors insulation?

A. Ammeter
B. Ohmmeter
C. Voltmeter
D. Megohmmeters

Answer 11

D. Megohmmeters

Question 12

The voltage drop across a 20 ohm resistor with 20 amp flowing would be _____ V.

A. 2
B. 0.5
C. 200
D. 20

Answer 12

C. 200

Question 13

Which unit is used to measure the magnitude of an electromotive force ?

A. Ohms
B. Volts
C. Electrons
D. Amps

Answer 13

B. Volts

Question 14

Low voltage systems may have an actual voltage variation of plus or minus:

A. 10%
B. 4%
C. 1.5%
D. 7.5 %

Answer 14

B. 4%

Question 15

Current flow is:

A. Increases as the applied voltage increases
B. Proportional to the resistance
C. Unaffected by resistance
D. Increases when applied voltage decreases

Answer 15

A. Increases as the applied voltage increases

Question 16

A voltmeter must _____ electrical circuit.

A. Offer low resistance to the
B. Offer no resistance to the
C. Offer slight resistance to the
D. Offer high resistance to the

Answer 16

D. Offer high resistance to the

Question 17

Extra low voltages include all voltages below ____V.

A. 30
B. 50
C. 110
D. 220

Answer 17

A. 30

Question 18

Atoms that have greater than 3 electrons in the outer shell are:

A. Positively charged
B. Good conductors
C. Neutrally charged
D. Poor conductors

Answer 18

D. Poor conductors

Question 19

An electrical distribution system is composed of service, feeders, and:

A. Secondary circuits
B. Primary circuits
C. Branch circuits
D. Trunk circuits

Answer 19

C. Branch circuits