mike holt exam prep unit 2
What's the resistance total of a 10-ohm, a 6-ohm, and a 3-ohm resistor connected in parallel? 0.60 ohms 1.67 ohms 19 ohms 180 ohms
1.67 ohms
The total resistance of three 6-ohm resistors in parallel is _____ ohms. 2 6 12 18
2
The total resistance of five 14-ohm resistors in parallel is _____ ohms. 2.33 2.8 14 70
2.8
The resistance of a coffee pot is 10 ohms and the resistance of a toaster oven is approximately 6 ohms. What's the total resistance of the two appliances if they're connected in parallel? 3.75 ohms 4 ohms 16 ohms 60 ohms
3.75 ohms
What's the voltage drop of 125 ft of 12 AWG wire (0.24 ohms) on a balanced 3-wire, 120/240V multiwire circuit supplying a 16A load? (remember round down unless it is a major fraction) 2.50V 3.80V 4.80V 6.70V
3.80V
What's the voltage drop of 180 ft of 12 AWG wire (0.347 ohms) supplying a 17A load? 2V 3V 4V 6V
6V
A 12-ohm coffee pot is connected in parallel to a 16.09-ohm skillet and wired with a wire having a resistance of 0.07 ohms. What's the total resistance of the loads and the wires of this series-parallel circuit? 7.04 ohms 14.08 ohms 16 ohms 36 ohms
7.04 ohms
A 115/230V rated dual-voltage motor connected to a 230V circuit must have the motor windings connected in series with each other so each winding will receive 230V. True False
False
When power supplies are connected in parallel, the voltage of the parallel-connected power supplies and the ampere-hour capacity of the parallel power supplies remain the same. True False
False
Series-parallel circuits are less confusing when broken down into a sequence of simple series and parallel problems then solving them by applying _____. Watt's Law Joule's Law Ohm's Law Coulomb's Law
Ohm's Law
An electrical circuit where there are two or more paths through which current can flow is called a _____ circuit. Parallel Series Multiwire branch Closed
Parallel
_____ circuits aren't used for building wiring, but they are used for equipment control circuits needing to be started or stopped from multiple locations. Parallel Series Multiwire branch Closed
Series
A series-parallel circuit is one that contains some circuit components connected in series and some components connected in parallel to each other. True False
True
Circuit wire voltage drop is caused by the resistance of the wires over the length of the path of the circuit as electrons return to the source. True False
True
Failure to terminate the phase wires of a multiwire branch circuit to different phases will cause neutral current from the circuits to be additive. True False
True
If the continuity of the neutral wire of a multiwire circuit is interrupted (opened), there could be a fire and/or destruction of electrical equipment resulting from either overvoltage or undervoltage of the circuits. True False
True
If the current flow through each phase wire of a multiwire circuit is the same, the neutral wire will carry 0A. This applies to 3-wire, 120/240V, single-phase and all three-phase circuits. True False
True
In a parallel circuit (ignoring voltage drop), the voltage across each resistance is equal to the voltage supplied by the power source. True False
True
In a parallel circuit, the total circuit resistance is always less than the smallest individual branch's resistance. True False
True
In a series circuit, the resistance of the circuit (RT) is equal to the sum of the series resistances. True False
True
One advantage of parallel circuits is that if one branch of a parallel circuit is opened, the power source still provides voltage to the remaining parallel branches. True False
True
Parallel circuits are used for the electrical wiring of receptacles, lighting, appliances, and equipment. True False
True
The NEC specifies that the continuity of the neutral wire of a multiwire branch circuit must not be dependent upon any wiring device. True False
True
The source voltage of a series circuit is equal to the sum of the voltages across all components of the series circuit. True False
True
The supply voltage of series-connected power supplies is equal to the sum of the voltage ratings of the individual power supplies. True False
True
The total amount of current flowing through a series circuit is always equal to the current flowing through the individual components of the circuit. True False
True
There are three methods for calculating the total resistance of a parallel circuit: The Equal Resistance method, the Product-Over-Sum method, and the Reciprocal method. True False
True
Three-wire, 120/240V, single-phase multiwire branch circuits are more cost effective than two 2-wire, 120V circuits because the 3-wire multiwire circuit has one less wire which permits the use of a smaller raceway. True False
True
Voltage drop can be reduced either by shortening the length of the wire or increasing the wire size to lower the wire's resistance. True False
True
In a series circuit the _____. total resistance (RT) is equal to the sum of the individual resistances in the circuit current is the same through all the circuit components sum of the voltages across all circuit components is equal to the applied voltage all of these
current is the same through all the circuit components sum of the voltages across all circuit components is equal to the applied voltage all of these
Kirchhoff's Law tells us that the total _____ of a parallel circuit is equal to the sum of the _____ of all the parallel circuit branches. voltage, voltage current, current resistance, resistance watts, watts
current, current
The neutral current returning to the power source of a 3-wire, 120/240V, single-phase circuit is _____ the difference in current flowing through the phase wires. equal to one-quarter one-third one-half
equal to
Overloading a wire will result in _____ which decreases the service life of the insulating material, and potentially result in a fire from arcing faults. nuisance tripping excessive heat dimming of lighting voltage drop
excessive heat
A(An) _____ branch circuit consists of two or more phase (hot) wires that have a voltage between them and an equal voltage between each phase wire and the neutral wire. multi-tap multiwire GFCI protected AFCI protected
multiwire
A(An) _____ is defined as the wire connected to the neutral point of a power source that's intended to return current from the load back to the power source under normal conditions. equipment grounding conductor grounding electrode conductor neutral wire system bonding jumper
neutral wire
Receptacles connected in parallel result in each receptacle having the same _____. operating capacity operating ampacity operating voltage current rating
operating voltage
When working with series-parallel circuits, you need to determine the _____ of the circuit by reducing it down from series to parallel until you have only one _____. voltage, voltage current, current resistance, resistance wattage, wattage
resistance, resistance
Current within a series circuit will _____ if any part of the circuit is open. create a short create a ground-fault stop flowing overheat
stop flowing
The neutral current returning to the power source of a 2-wire circuit is _____ the current flowing out of the power source. the same as one-quarter one-third one-half
the same as
In a parallel circuit _____. the total resistance is always less than the smallest resistor in the circuit the sum of the currents is equal to the total current that flows from the power source voltage across each component is the same all of these
the total resistance is always less than the smallest resistor in the circuit the sum of the currents is equal to the total current that flows from the power source voltage across each component is the same all of these
