Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
50 Cards in this Set
- Front
- Back
|
The working voltage of a capacitor in an ac circuit should be?
A. equal to the highest applied voltage B. at least 20 percent greater than the highest applied voltage c. at least 50 percent greater than the highest applied voltage |
c. at least 50 percent greater than the highest applied volatge |
|
|
The term that describes the combined resistive forces in an ac circuit is
A. resistance B. reactance C. impedance |
C. Impedance |
|
|
The basis for transformer operation in the use of alternating current is mutal
A. Inductance B. Capacitance C. reactance |
A. inductance |
|
|
The opposition offered by a coil to the flow of alternating current is called (disregard resistance)
A. Impedance B. reluctance C. inductive reactance |
C. inductive reactance |
|
|
An increase in which of the following fatctors will cause an increase in the inductive reactance of a circuit?
A. Inductance and frequency B. Resistance and voltage C. resistance and capacitive reactance
|
A. inductance and frequency |
|
|
(refer to figure 1) When different rated capacitors are connected in series in a circuit, the total capacitance is
A. less than the capacitance of the lowest rated capacitor B. greater than the capacitance of the highest rated capacitor C. equal to the sum of the capacitances |
C. equal to the sum of the capacitances |
|
|
Capacitors are sometimes used in dc circuits to
A. counteract inductive reactance at specific locations B.smooth out slight pulsations in current/voltage C. assist in stepping voltage and current up and/or down |
B. Smooth out slight pulsations in current/voltage |
|
|
In an ac circuit, the effective voltage is
A. equal to the maximum instantaneous voltage B. greater than the maximum instantaneous voltage C. less than the maximum instantaneous voltage |
C. less than the maximum instantaneous voltage |
|
|
The amount of electricity a capacitor can store is directly proportional to the
A. distance between the plates and inversely proportional to the plate area B. plate area and is not affected by the distance between the plates. C. plate area and inversely proportional to the distance between the plates |
C. plate area and inversely proportional to the distance between the plates |
|
|
(refer to figure 2) What is the total capacitance of a certain circuit containing three capacitors with capacitances of .02 microfarad, .05 microfarad, and .10 microfarad, respectively?
A. .170 F B. 0.125pF C. .0125 F |
C. .0125 F |
|
|
unless otherwise specified, any values given for current or voltage in an ac circuit are assumed to be
A. instantanous values B. effective values C. maximum values |
B. effective values |
|
|
when different rated capacitors are connected in parallel in a circuit the total capacitance is (note: C(T) = C(1) + C(2) + C(3)....)
A. less than the capacitance of the lowest rated capacitor B. equal to the capacitance of the hightest rated capacitor C. equal to the sum of all the capacitances |
C. equal to the sum of all the capacitances |
|
|
when inducors are connected in series in a circuit, the total inductance is (where the magnetic fields of each inductor do not affect the others) (note: L(T) = L(1) + L(2) + L(3)....)
A. less than the inductance of the lowest rated inductor B. equal to the inductance of the highest rated inductor C. equal to the sum of the individual inductances |
C. equal to the sum of the individual inductances. |
|
|
(refer to figure 3) WHen more than two inductors of different inductances are connected in parallel in a circuit, the total inductance is
A. less than the inductance of the lowest rated inductor B. equal to the inductance of the highest rated inductor C. equal to the sum of the individual inductances |
A. less than the inductance of the lowest rated inductor |
|
|
What is the total capacitance of a certain circuit containing three capacitors with capacitances of .25 microfarad, .03 microfarad, and .12 microfarad respectively? (note: C(T) = C(1) + C(2) + C(3))
A. .4 F B. .04 pF C. .04 F |
A. .4 F |
|
|
Which requires the most electrical power during operation? (Note: 1 horsepower = 746 watts)
A. A 12 volt motor requiring 8 amperes B. four 30 watt lamps in a 12 volt parallel circuit C. two lights requiring 3 amperes each in a 24 volt parallel system |
C. two lights requring 3 amperes each in a 24 volt parallel system |
|
|
How much power must a 24 volt generator furnish to a system which contains the following loads? one motor (75 percent efficent) 1/5 hp three position lights 20 watts each one heating element 5 amp one anticollision light 3 amp (note: 1 horsepower = 746 watts)
A. 402 watts B. 385 watts C. 450 watts |
C. 450 watts |
|
|
A 12 volt electric motor has 1,000 watts input and 1 horsepower output. Maintaining the same effciency, how much input power will a 24 volt, 1 horsepower electric motor require?
A. 1000 watts B. 2000 watts C. 500 watts |
A. 1000 watts |
|
|
how many amperes will a 28 volt generator be required to supply a circuit containing five lamps in parallel, three of which have a resistance of 6 ohms each and two of which have a resistance of 5 ohms each?
A. 1.11 Amperes B. 1 ampere C. 25.23 amperes |
C. 25.23 amperes |
|
|
A 1 horsepower, 24 volt dc electric motor that is 80 percent efficient requires 932.5 watts. how much power will a 1 horsepower, 12 volt dc electric motor that is 75 percent efficient require? (note: 1 horsepower = 746 watts)
A. 932.5 watts B 1,305.5 watts C. 994.6 watts |
C. 994.6 watts |
|
|
The potential difference between two conductors which are insulated from each other is measured in
A. volts B. amperes C. coulombs |
A. volts |
|
|
A 24 volt source is required to furnish 48 watts to a parallel circut consisting of four resistors of equal value. What is the voltage drop across each resistor?
A. 12 volts B. 6 volts C. 24 volts |
C. 24 volts |
|
|
When calculating power in a reactive or inductive ac circuit, the true power is
A. More than the apparent power B. less than the apparent power in a reactive circuit and more than the apparent pwer in an inductive circuit C. less than the apparent power. |
C. less than the apparent power. |
|
|
. |
. |
|
|
(refer to figure 5) what is the impedance of an ac-series circuit consisting of an inductor with a reactance of 10 ohms, a capacitor with a reactance of 4 ohms, and a resistor with a resistance of 8 ohms?
A. 22 ohms B. 5.29 ohms C. 10 ohms |
C. 10 ohms |
|
|
refer to figure 6. If resistor R(5) is disconnected at the junction of R(4) and R(3) as shown, what will the ohmmeter read?
A. 2.76 ohms B. 3 ohms C. 12 ohms |
B. 3 ohms |
|
|
(Refer to figure 7) If resistor R(3) is disconnected at terminal D, what will the ohmmeter read?
A. infinite resistance B. 10 ohms C. 20 ohms |
A. infinite resistance |
|
|
(refer to figure 8) With an ohmmeter connected into the circut as shown, what will the ohmmeter read?
A. 20 ohms B. infinite resistance C. 10 ohms |
C. 10 ohms |
|
|
(refer to figure 9) How many instruments (voltmeters and ammeters) are installed correctly?
A. Three B. One C. Two |
C. two |
|
|
The correct way to connect a test voltmeter in a circuit is
A. in series with a unit B. between the source voltage and the load C. In parallel with a unit |
C. In parallel with a unit |
|
|
Which term means .001 ampere?
A. Microampere B. kiloampere C. Milliampere |
C. Milliampere |
|
|
A cabin entry light of 10 watts and a dome light of 20 watts are connected in parallel to a 30 volt source. If the voltage across the 10-watt light is measured, it will be
A. equal to the voltage across the 20-watt light B. half the voltage across the 20-watt light C. one-third of the input voltage
|
A. equal to the voltage across the 20 watt light |
|
|
A 14 ohm resistor is to be installed in a series circuit carrying .05 ampere. How much power will the resistor be required to dissipate?
A. At least .70 milliwatt B. At least 35 milliwattsss C. Less than .035 watt |
B. at least 35 milliwatts |
|
|
.002kv equals
A. 20 volts B. 2.0 volts C. .2 volt |
B. 2.0 volts |
|
|
(refer to figure 10) What is the measured voltage of the series-parallel circut between terminals A and B?
A. 1.5 volts B. 3.0 volts C. 4.5 volts |
B. 3.0 volts |
|
|
A 24-volt source is required to furnish 48 watts to a parallel circuit consisting of two resistors of equal value. What is the value of each resistor?
A. 24 ohms B. 12 ohms C. 6 ohms |
A. 24 ohms |
|
|
Which requires the most electrical power? (note: 1 horsepower = 746 watts)
A. A 1/5 horsepower, 24 volt motor which is 75 percent efficient B. Four 30 watt lamps arranged in a 12 volt parallel circuit C. A 24 volt anticollision light circuit consisting of two light assemblies which require 3 ameres each during operation |
. |
|
|
what unit is used to express electrical power?
A. volt B. Watt C. Ampere |
B. watt |
|
|
What is the operating resistance of a 30-watt light bulb designed for a 28-volt system?
A. 1.07 ohms B. 26 ohms C. 0.93 ohm |
B. 26 ohms |
|
|
which statement is correct when made in reference to a parallel circuit?
A. The current is equal in all portions of the circuit B. The total current is equal to the sum of the currents through the individual branches of the circuit. C. The current in amperes can be found by dividing the EMF in volts by the sum of the resistors in ohms |
B. The tota current is equal to the sum of the currents through the individual branches of the circuit |
|
|
Which of the following are commonly used as rectifiers in electrical circuits? 1. Anodes 2. Cathodes 3. Diodes
A. 3,1 B. 3,2 C. 3
|
C. 3 |
|
|
Diodes are used in electrical power supply circuits primarily as
A. switches B. rectifiers C. relays |
B. rectifiers |
|
|
Transfer of electric energy from one circuit to another without the aid of electrical connections
A. is called induction B. is called capacitance C. can cause excessive arcing and heart and as a result is impractical for use only with low voltages /amperages |
A. is called induction |
|
|
if three resistors of 3 ohms, 5 ohms, and 22 ohms are connected in series in a 28 volt circuit, how much current will flow through the 3 ohm resistor?
A. 9.3 amperes B. 1.05 amperes C. 0.93 ampere |
C. 0.93 ampere |
|
|
A circuit has an applied voltage of 30 volts and a load consisting of a 10 ohm resistor in series with a 20 ohm resistor. What is the voltage drop across the 10-ohm resistor?
A. 10 volts B. 20 volts C. 30 volts |
A. 10 volts |
|
|
(refer to figure 11) Find the total current flowin in the wire between points C and D
A. 6.0 amperes B. 2.4 amperes C. 3.0 |
C. 3.0 amperes |
|
|
(refer to figure 11) Find the voltage across the 8-ohm resistor.
A. 8 volts B. 20.4 volts C. 24 volts |
C. 24 volts |
|
|
(refer to figure 12) find the total resistance of the circuit
A. 16 ohms B. 2.6 ohms C. 21.2 ohms |
C. 21.2 ohms |
|
|
Which is correct in reference to electrical resistance?
A. Two electrical devices will have the same combined resistance if they are connected in series as they will have if connected in parallel.
B. If one of three bulbs in a prallel lighting circuit is removed, the total resistance of the circuit will become greater.
C. An electrical device that has a high resistance will use more power than one with a low resistance with the same applied voltage. |
B. If one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater. |
|
|
What happens to the current in a voltage step up transformer with a ratio of 1 to 4?
A. The current is stepped down by 1 to 4 ratio B. The current is stepped up by a 1 to 4 ratio C. the current does not change |
A. The current is stepped down by 1 to 4 ratio |
