Year 2 Semester 1 Electrical Delmars
In a series RL circuit, Et=120V, R=500 ohms, XL=500. What is the true power?
14.4W
A circuit has four resistors connected in series. If each resistor has a voltage drop of 60 V, what is the voltage applied to the circuit?
240 V
At what angle does the voltage reach its maximum negative value on a sine wave?
270 degress
How many degrees are there in one complete sine wave?
360 degrees
A partially protected area, such as an open porch, or under a roof or canopy, is a dry location.
False
Reactive power is measured in __________________?
VARS
What is the most common type of AC waveform?
sine wave
A location exposed to the weather is a ____ location.
wet
Install luminaires listed for ____ locations if they will be subject to shower spray.
wet
When using nonmetallic boxes, the volume allowance is based on ____.
wiring devices cable clamps equipment grounding conductors
How many degrees are the current and voltage out of phase with each other in a pure resistive circuit?
0 degrees
An AC waveform has a frequency of 50 Hz. How much time is required to complete one cycle?
0.02 S
Three inductors are connected in parallel. Inductor 1 has an inductance of 0.06 H; Inductor 2 has an inductance of 0.05 H; and Inductor 3 has an inductance of 0.1 H. What is the total inductance of this circuit?
0.0214 henry
An inductor is connected to a 240-V, 1000-Hz line. The circuit current is 0.6 A. What is the inductance of the inductor?
0.0637 H
A circuit has three resistors connected in series. Resistor R2 has a resistance of 220 ohms and a voltage drop of 44 V. What is the current flow through resistor R3?
0.2 A
An inductor with an inductance of 3.6 H is connected to a 480-V, 60-Hz line. How much current will flow in this circuit?
0.354 A
What are the three rules for series circuits?
1. The current is the same at any point in the circuit. 2. The total resistance is equal to the sum of the individual resistors. 3. The applied voltage is equal to the sum of the voltage drops across all the resistors.
Ceiling fan speed can be controlled by a ____.
1. pull chain on the fan 2. speed control mounted in a wall box 3. remote control similar to TV/VCR type
For hallways of ____________________ ft. or more in length, it is required to have at least one receptacle outlet.
10 ft
An inductive reactance of 150 ohms and a Q of 12, what is the amount or wire resistance of the inductor. R=Xl/Q
12.5
A sine wave has a maximum value of 560 V. At what angle of rotation will the voltage reach a value of 123 V?
12.69 degrees
An AC waveform completes one cycle in 0.8 mS. What is the frequency of the waveform?
1250 Hz
A sine wave has a maximum value of 230 V. What is the voltage after 388 of rotation?
141.6 V
An R-L series circuit has an apparent power of 230 VA and a true power of 180 W. What is the reactive power?
143.18 VARs
An R-L series circuit has a reactive power of 1234 VARs and an apparent power of 4329 VA. How many degrees are voltage and current out of phase with each other?
16.46 degrees
An R-L series circuit has a power factor of 73%. If the apparent power is 560 kVA, what is the true power in the circuit?
163, 520 watts
An inductor has an inductive reactance of 250 V when connected to a 60-Hz line. What will be the inductive reactance if the inductor is connected to a 400-Hz line?
1666.7 R
A sine wave has a voltage of 63 V after 228 of rotation. What is the maximum voltage reached by this waveform?
168.18 V
Four inductors, each having an inductance of 0.6 H, are connected in series. What is the total inductance of the circuit?
2.4 henrys
A series circuit contains five resistors. The total voltage applied to the circuit is 120 V. Four resistors have voltage drops of 35 V, 28 V, 22 V, and 15 V. What is the voltage drop of the fifth resistor?
20 V
The NEC permits all bathroom receptacles to be on a single ____ branch circuit so long as it doesn't supply other loads.
20 ampere
Receptacle outlets must be installed in any wall space ____ or more in width.
24 in (600 mm)
Four resistors having a value of 100 ohms each are connected in parallel. What is the total resistance of the circuit?
25 Ohms (R) R= 1/[(1/R1)+(1/R2)+...+(1/Rn)] for parallel Circuits
A sine wave has a peak-to-peak value of 88 V. What is the average value?
28.03 V
Ceiling-suspended paddle fans must not be located within a zone measured ____ horizontally and ____ vertically from the top of the bathtub rim or top of a shower stall threshold.
3 ft (900 mm); 8 ft (2.5 m)
Hanging light fixtures must be kept at least _________________ feet horizontally and _________________ feet vertically from the edge of the tub rim.
3, 8
An inductor with an inductance of 0.06 H is connected to a 480V, 400 Hz line. How much current will flow in this circuit? (XL=2"FL) (I=E/XL)
3.18 A
A parallel circuit contains four branches. One branch has a current flow of 0.8 A, another has a current flow of 1.2 A, the third has a current flow of 0.25 A, and the fourth has a current flow of 1.5 A. What is the total current flow in the circuit?
3.75 A
An R-L series circuit has a power factor of 86%. How many degrees are the volt-age and current out of phase with each other?
30.68 degrees
A sine wave has a peak value of 433 V. What is the RMS value?
306.13 V
A 120V, 60Hz AC circuit is connected to an inductor. The current flow in the circuit is 0.35A. What is the inductive reactance? (E/I)
342.9 Ohms
When an AC generator rotor makes one complete rotation, the generated waveform will have gone through how many electrical degrees?
360 Degrees
An inductor with an inductive reactance of 48 ohms is connected is series with a resistor with a value of 32 ohms. What is the total impedance of this circuit?
57.7 Ohms
The resistor in an R-L series circuit has a voltage drop of 53 V, and the inductor has a voltage drop of 28 V. What is the applied voltage of the circuit?
59.94 V
How many hertz is the standard generated in the United States?
60 Hz
Three inductors are connected in series. Their values of inductance are: L1=0.5H, L2=0.4H, and L3=0.8H. If these inductors are connected to a 60Hz line, what will the total inductive reactance of the circuit be? (2"FL) (L1+L2+L3+...)
640.9 Ohms
The outlet box or outlet box system of a ceiling-suspended fans must not support more than ____ pounds.
70
A series circuit has individual resistor values of 200, 86, 91,180, and 150 ohms . What is the total resistance of the circuit? ___________ohms
707
A DC voltage has an average value of 68 V. What is the RMS value?
75.56 V
If the three inductors, Inductor 1 has an inductance of 0.06 H; Inductor 2 has an inductance of 0.05 H; and Inductor 3 has an inductance of 0.1 H. were connected in series, what would be the inductive reactance of the circuit? Assume the inductors are connected to a 60-Hz line.
79.17 R
Choose a measurement of an AC sine wave (Not degrees). Average Angle Frequency Strength
Average
AC current will do what to its direction on a periodic basis?
Change
What is the relationship of the current and voltage in a pure resistive circuit?
Current and voltage are in phase
A parallel circuit is one which has only one path for current flow
False
If a waveform has an instantaneous voltage of 237V at 293 degrees, the peak voltage is 237/sin293=-277.4674244
False
The number of half cycles of AC voltage that occur in 1 s is frequency.
False
Three rules concerning parallel circuits are: 1. The total current flow in the circuit is the result of subtracting the currents from the resistance. (False) 2. The voltage drop across any branch of a parallel circuit is the same as the applied voltage. 3. The total resistance of a parallel circuit is alwaysless than the resistance of the lowest value resistor, or branch in the circuit.
False
What is the relationship of voltage and current (concerning phase angle) in a pure inductive circuit?
The current lags the voltage by 90
What is the relationship of voltage and current (concerning phase angle) in a pure resistive circuit?
The voltage and current are in phase with eachother.
AC power can be transmitted at lower amperages and changed to useful amperages at the load by the use of what?
Transformer
Although it adds cost, consider a(n) outdoor weatherproof receptacle on both sides of the front door for easy plugging in of outdoor decorations.
True
Circuits in homes are connected in parallel because if lights were connected in series, they would all need to be turned on. If one light burned out, they all would go out. If receptacles were connectedin series, a device would have to be connected in every receptacle before any one device couldoperate.
True
Fan speed controllers have internal circuitry that is engineered specifically for use on inductive circuits. Do not use a standard incandescent lamp dimmer to control fan motors.
True
If an AC resistive circuit has a peak voltage of 170V and an effective current of 10 amperes, the effective power is 1201.9W.
True
Inductance of the inductor and the frequency means the inductive reactance is proportional.
True
The peak voltage of a 120-V (effective), AC is 120/.707=169.7312588
True
The ratio of true power to apparent power is power factor.
True
True power can only be produced when voltage and current are in phase.
True
When replacing an existing luminaire (fixture) with a ceiling-suspended paddle fan, make sure that the existing outlet box is listed and marked as suitable for fan support.
True
When using nonmetallic-sheathed cable or armored cable, never use the bare equipment grounding conductor as a grounded circuit conductor, and never use the grounded circuit conductor as an equipment grounding conductor.
True
Power factor (PF) is the ratio of the ___________ power to the ___________ power.
True, apparent
Of the different power values in a RL circuit, which is known as wattless power?
VARs
According to NEC 406.9, receptacles ____ permitted to be installed in bathtub and shower spaces.
are not
The selection of outlet boxes and switch boxes is made by the electrician. These decisions are based on Code requirements, space allowances, good wiring practices, and ____.
common sense
NEC 410.10(D) ____ lighting track to be located within a zone measured 3 ft (900 mm) horizontally and 8 ft (2.5 m) vertically from the top of a bathtub rim or top of a shower stall threshold.
does not permit
With ____ products, it takes two failures to create a shock hazard to the user.
double insulated
During the winter, it is suggested that a paddle fan should ____.
draw air up
Some types of panels and similar building elements are considered wall space when figuring receptacle spacing, and others are not.
fixed room divider ---- Receptacles required sliding glass panel ---- Receptacles not required fixed glass panel ---- Receptacles required
When installing a ceiling paddle fan, the outlet box must be ____.
listed and marked as acceptable for fan support
A light dimmer ____ be used as a speed control for a ceiling fan or other motor.
should not
A bathroom is defined as "an area including a basin, with one or more of which items?
toilet tub bidet
In a series RL circuit, Et=120V, R=40 ohms, XL=30 ohms. What is Er?
96V
As defined in Article 100, a bathroom is required to have a ____.
basin
The suggested fan size for rooms up to 144 square feet is ____________________ inches, and the suggested fan size for rooms up to 500 square feet is ____________________ inches.
42, 56
Some inspectors consider the area within a ____ angle from a roof line or overhang to be a damp location.
45 degrees
An inductor has an inductive reactance of 80 ohms and a wire resistance of 14 ohms. What is the Q of the inductor?
5.714
An inductor has a wire resistance of 6 ohms. The Q of the inductor is 9. Using the formula: XL=Q X R determine the inductive reactance of the inductor.
5.714 R
Three inductors connected in parallel have inductances of 0.75H, 0.50H, and 0.60H. If these inductors are connected to a 400 Hz line, what will be the total inductive reactance of the circuit?
502.6 Ohms
How many degrees are the current and voltage out of phase with each other in a pure inductive circuit?
90 degrees
A phase angle meter connected in an R-L series circuit indicates that the current is 28 degrees out of phase with the voltage. What is the circuit power factor
92.7%
A 0.25H inductor is connected to a 120V, 60Hz line. What is the inductive reactance of this circuit? (2"FL)
94.3 Ohms
What electrical quantity is the unit of Inductance?
Henry
What would limit the amount of current flow in a pure inductive circuit?
Inductive Reactance
What does "in phase" mean when discussing voltage and current?
It means that the voltage and the current are both positive and negative at the same time.
Lighting fixtures intended for installation in wet locations must be ____.
Marked "suitable for Wet Locations"
Recessed or surface-mounted luminaires and recessed exhaust fans ____ be located within the restricted zone near the bathtub.
May
Choose a measurement of an AC sine wave (Not degrees). Frequency Angle Peak Micron
Peak
Choose a measurement of an AC sine wave (Not degrees). Peak to Peak Angle Frequency Positive
Peak to Peak
Choose a measurement of an AC sine wave (Not degrees). Angle Frequency RMS Negativity
RMS
Which of the following is NOT a reason that ceiling fans must be specially supported? Weight Torque (twisting motion, particularly when first starting) Vibration Safe grounding (Answer)
Safe grounding
