Study exam
Calculate the total power consumed by the circuit shown in the figure. R1 75 R2 150
288 watts
You are installing 6 new 750 watt parking lot lights at a church. There are no prints available. How many 20 ampere circuits will you need if the breaker(s) cannot be loaded more than 80%? The lights operate on 120 volts.
3 circuits
What is the voltage drop across R3 in the figure?
3.15 volts
What is the total current for the circuit shown in the figure below?
3/4 Amps
A 120 volt kitchen circuit is rated for 20 amps. A microwave oven rated at 1.5 kW and a 350 watt toaster are connected to the circuit. If you add a coffee maker rated at 600 watts and run all of these appliances at the same time, how much (in amps) will this circuit be overloaded? (Breakers cannot be loaded more than 80% of their rated value.)
4.42 amps
The current induced in the windings of a transformer is inversely proportional to the number of turns of wire in the windings. What is the current in the secondary winding which has 1200 turns when the primary has 300 turns and a current of 18 amps?
4.5 amps
For the circuit in the figure below, if the source voltage is 120 V, and the voltage across R1 is 80 V, what is the voltage across R2?
40 volts
What is the current rating for branch L1 of the circuit shown in the figure?
420 milliamps
What is the total current for the circuit shown in the figure below?
429 milliamps
How much power is dissipated by R3 for the circuit shown in the figure?
47.85 watts
The voltage induced in the windings of a transformer is directly proportional to the number of turns of wire in the windings. What is the voltage in the secondary winding which has 500 turns when the primary has 2500 turns and an applied voltage of 2400 volts?
480 volts
What is the total resistance of a circuit with six 30 ohm resistors in parallel?
5 ohms
Calculate the total resistance of a circuit with a 10 ohm, 20 ohm, and 30 ohm resistor in parallel.
5.45 ohms
What is the current through R1 for the circuit shown in the figure?
514 milliamps
Determine the total resistance of the circuit shown in the figure below. Given: R1 = 4 Ω, R2 = 10 Ω, R3 = 15 Ω, R4 = 30 Ω
59 ohms
If In in the Norton equivalent circuit in the figure below is 18 amps, and RN is 6 Ω, what would be the current through RL if RL = 12 Ω?
6 amps
In a series circuit the voltage drop across a resistor is proportional to its resistance. If the resistance of R1 is 100 ohms, and voltage across it is 2 volts, what is the voltage across R2 if its resistance is 300 ohms?
6 volts
The NEC states the resistance of 4/0 coated copper conductors is 0.0626 ohms per 1000 feet. What would be the total resistance of the three 4/0 conductors installed in parallel, if the total length for each of the three conductors is 323 feet?
6.7 milliohms
The ratio of apprentices to journeymen on a specific project is 1 to 3. There are 180 journeymen employed on the project. How many apprentices are employed?
60
Using the product over sum method, calculate the total resistance of a circuit with a 100 ohm and a 200 ohm resistor in parallel.
66.67 ohms
.How many amps are flowing in the black wire for the circuit shown in the figure?
8 amps
You are servicing a fire alarm panel and discover that the 24 volt, 2 amp-hour back-up battery is dead and cannot be recharged. You decide to supply the back-up functions temporarily with 6-volt, 1.25 amp-hour batteries while you order a replacement for the original battery. How many temporary batteries will you need for this job?
8 batteries
How many amps are flowing in the red wire for the circuit shown in the figure?
8.5 amps
What is the current rating for branch L2 of the circuit shown in the figure?
830 milliamps
Calculate the total resistance of a circuit with a 20 ohm, 30 ohm, and 40 ohm resistor in parallel.
9.2 ohms
In a generator, maximum positive voltage is induced at __________ degrees of armature rotation and maximum negative voltage is induced at __________ degrees.
90/270
The ceiling fixtures in the three bedrooms of a home are supplied by one 120 volt parallel circuit. Each fixture is equipped with four 75 watt lamps. What is the total power consumed by the bedroom lighting?
900 watts
Which symbol in the figure below represents a strainer on a piping print?
Symbol A
Which symbol in the figure represents a surface mounted incandescent fixture?
Symbol D
Which scale is based on relations such as 1/4" = 1', or 1/8" = 1'?
architect's
Which scale is normally used for drawing large plot or site plans with scales like 1" = 50'
civil engineer's
The Superposition Method is based on the fact that the current at any point in a circuit is the sum of the ____________________ caused by each of the power sources.
current
When applying the "left hand rule for generators", the center finger points in the direction of ____________________.
current flow in the armature
Which scale is based on tenths and hundredths of an inch?
decimal
The face view of a building or residence can be seen on a(n) ____________________ plan.
elevation
Where is the best place to find the locations and heights of exterior lights?
elevation
A(n) _____________________ is a type of circle that is elongated in one dimension.
ellipse
Where would you find information relating to voltage and power requirements for specific motors, compressors, and machinery?
equipment schedule
When it is necessary to check the print reproduction scale, you should verify at least one ________________________ dimension.
horizontal and one vertical
Increasing the level of the applied voltage to a combination resistive circuit will result in a(n) _____________ in the voltage drop across all resistive components.
increase
Which of the following is a ferromagnetic metal?
iron
A(n) _______________ projection recedes at 30 degrees in both directions.
isometric
If a set of prints incorporates non-standard or job specific symbols, it should also contain a _____________________.
legend or symbol library
Which branches of the circuit shown in the figure will have the same amount of voltage drop?
R2,R3,4
___________ is the only electrical element in a combination circuit that consumes power.
Resistance
A customer asks you to install an attic vent fan powered by a 110 volt, 1/4 hp motor and wants you to tell him approximately how much it will cost him to operate it per day. Power in his area costs about six and a quarter cents per kilowatt hour.
$0.28 per day221
Suppose an Electrical Worker needed to provide a cost estimate for a house with 223 outlets (sometimes referred to as box openings). The estimate does not include lighting fixtures, but does include all wired devices and outlets. Dimmers and time switches are extra. One 100 amp 240-volt service is included. One central furnace or one central heat pump without auxiliary heat is included. One telephone outlet, one TV outlet, and one electric water heater outlet are included. Devices are standard ivory with plastic plates. All wiring and material is full accordance with the NEC and local codes and is guaranteed for one year. Electrical permit and inspection fee is included. Using a cost estimating value of $30.00 for each electrical box opening, how much would the electrical installation estimate on this house cost (counting two gang boxes as two openings)?
$6,690.00
In the figure, identify the sets of resistors that are in series.
(R1, R2)(R3, R4)(R5, R6)(R7, R8)
What is the current through R1 for the circuit shown in below figure?
.48 amps
How many amps are flowing in the neutral conductor for the circuit shown in the figure?
.5 amps
Using the principle of superposition, determine the total current of the circuit shown in the figure. Given: E1 = 24V, E2 = 6V, R1 = 18Ω, R2 = 12Ω
.6 amps
Determine the total resistance for the circuit shown in the figure below. Given: R1 = 2 Ω, R2 = 4 Ω, R3 = 6 Ω, R4 = 2 Ω
.7 ohms
What is the current through each resistor in a circuit with three 24-ohm resistors connected in parallel supplied by two 12-volt batteries, also wired in parallel?
0.50 amps
In the figure, how much power would be consumed in R4 if the supply voltage is 220 volts? Given: R4 = 30 Ω
1.6 kilowates
In the circuit shown in the figure, what is the voltage across R2?
10 volts
If the supply voltage for the circuit shown in the figure below is 120 volts, the current through R2 would be _______________ amperes. Given: R2 = 10 Ω
12 amps
Using the Law of Proportionality, find the supply voltage for a series circuit containing the following loads: R1 = 100 ohms, R2 = 250 ohms, R3 = 300 ohms Given: voltage drop across R2 = 4.6 volts
12 volts
The voltage induced in the windings of a transformer is directly proportional to the number of turns of wire in the windings. What is the applied voltage in the primary winding which has 1200 turns when the secondary has 240 turns and a voltage of 24?
120 volts
What is the voltage drop across R4 for the circuit shown in the figure?
13.5
You're installing an intercom system to the front gate of an estate. It operates on 24 volts, ± 1 volt, and draws 0.2 amps. The power supply is located in the master unit, 450 feet away. What is the smallest copper wire (in cmil) you can use to run this circuit? Given: Kcopper = 10.4
1870 cmil
How much current would flow in a circuit with two 24 volt sources connected in parallel supplying power to a 12 ohm load?
2 amperes
Using the Law of Proportionality, calculate the voltage drop across R1 for the circuit shown in the figure?
2.3 volts
Using the Law of Proportionality, find the total current for the circuit shown in the figure when the current through one branch is known.
2.30 amps
What is the equivalent resistance of the circuit shown in figure? Given: R1 = 8 Ω, R2 = 8 Ω, R3 = 10 Ω, R4 = 8 Ω
20.44 ohms
What is the supply voltage for the circuit shown in the figure below if the current through R1 is 50 amperes? Given: R1 = 4 Ω
200 volts
What is the voltage drop across R1 for the circuit shown in the figure?
22.5 volts
Using the law of proportionality, find the current through R2 for the circuit shown in the figure.
225 amps
In the figure, how much power would be consumed in R2 and R3 combined if the supply power is 120 volts? Given: R2 = 10 Ω, R3 = 15 Ω
2400 watts
In which branch of a parallel circuit is the greatest amount of power consumed?
Branch of least resistance
Which one of the circuits in the figure below represents a typical Thevenin's equivalent circuit?
Circuit A
_________ generators use a commutator to apply voltage to an external circuit, where _________ generators use slip rings
DC/AC
Graphite is an example of a(n) _____________ material.
Diamagnetic
When measuring for the back to back 90 degree bends shown, the correct dimension is taken from which two points?
F-A
The ___________________ is the print most commonly used by the electrician
Floor plan
A basic law of physics states that whenever an electric current _____________________ a conductor a magnetic field is formed around the conductor.
Flows through
What is the difference between the flow direction arrow for hydraulic prints and pneumatic prints?
Hydraulic arrows are darkened in, pneumatic arrows are only outlined.
In a series-parallel (combination) circuit, the total power can be found by using the formula __________?
PT = ET x IT
One form of Kirchhoff's Law states that the algebraic sum of the_____________ in a closed circuit must equal zero.
Voltage drop
Norton's Theorem states that any two-terminal source can be reduced to a maximum ________________ and an equivalent parallel resistance.
Wattage
A(n) ______________ projection has a standard front view and recedes usually at 45 degrees.
oblique
Standard blueprint plans and elevations are generally drawn in _______________ projection.
orthographic
If a conductor is moving __________ to the flux lines, zero volts will be induced.
parallel
In a _____________ circuit the current may split and flow in two or more different paths.
parallel
The total resistance of a ________________ circuit is less than the value of the lowest value resistor.
parrellel
The best place to find the location of the electrical service and related information, would be on the ________________________.
plot plan
The Superposition Method is used by analyzing a circuit one____________________ at a time.
power source
Which is the most important reason for an electrician to understand symbols used for mechanical systems?
preventing conflicts with electrical runs
When batteries are connected in parallel, their voltages ____________ and their amp-hour capacities are added.
remain the same
In residential construction it is common for the electrical contractor to determine the number of circuits required and to produce load ___________________.
schedules
In a ___________ circuit the current through each component is equal to the total circuit current.
series
What type of print is used by the electrician to determine building orientation and location of exterior lighting?
site or plot plan
A list of detailed job requirements, under which all work must be performed is known as the __________________.
specifications
When not clarified by the prints, specifications or codes, device mounting heights are determined by _________________________.
standard practice
The total resistance of a parallel circuit is the reciprocal of the _______________ of the reciprocals of the individual resistances.
sum
In a combination circuit, the current leaving the source is ________________ the current returning to the source.
the same as
The total power consumed in a parallel circuit is ____________________ the power consumed in each branch.
the sum of
What happens to the supply voltage in a combination (series/parallel) circuit?
the total voltage is dropped across the component
Unless otherwise noted, the overall scale for a typical floor plan is most likely shown within the ____________________.
title block
Batteries of different ___________ should never be connected in parallel.
voltage
When scaling a print you must remember that ______________ always supersede scaled dimensions.
written dimensions
