Basic Electricity
.535 Millivolts
.535V is
Output device
A motor is a type of electrical ___________________.
5.5Ω
A parallel circuit has 3 resistors. R1=10Ω, R2=20Ω, and R3=30Ω. What is the total resistance of the circuit?
14.85A
Find the current. 208 Volts, 14Ω
18.5Ω
Find the resistance. 13 Volts, 0.7 Amps
132.4Ω
Find the total inductive reactance in a parallel circuit where XL1=940Ω, XL2=231. and XL3=464Ω.
71.4
Find the voltage. Resistance is 17Ω and current is 4.2.
Parallel
In a __________________ circuit, the voltage available to each branch is equal to the source voltage.
Autotransfomer
Only has one coil for both primary and secondary
Voltage
Potential difference refers to _____________________.
Watts
Power is measured in ________________________.
14.4 Amps
What is the current?
To resist changes in current flow
What is the purpose of an inductor?
Yes - but the circuit will operate with reduced current
Will a parallel circuit operate if one of its branches has an open?
.625
What is the total resistance?
Farad
What is the unit of measurement for capacitance?
Henry's
What is the unit of measurement for inductance?
1,000,000 - Mega
What is the value of the prefix M?
1,000
What is the value of the prefix k?
1/1000th - Milli
What is the value of the prefix m?
1/1,000,000th - Micro
What is the value of the prefix µ?
1.5V
What is the voltage drop across each lamp? (C batteries are 1.5V)
Circuit breaker
What is this symbol?
Run capacitor
What is used to continuously adjust current or phase shift to a motors windings in an effort to optimize the motor's torque and efficiency performance?
Parallel
What type of circuit is this?
Wye
What type of circuit is this?
Variable Resistor
What type of resistor can be adjusted?
Alexandro Volta
Who invented the battery?
Thomas Edison
Who invented the light bulb?
Andre Ampere - Founder of amperage
Who is this?
George Simon Ohm
Who is this?
Nikola Tesla - Founder of AC Current
Who is this?
Thomas Edison - Invented the light bulb
Who is this?
Thomas Edison - Edison was a proponent of DC current instead of AC current
Who was Tesla's rival?
Start windings
Which type of windings draw heavy current at startup on a motor?
Start windings
Which windings on a single phase motor are pulled out of the circuit by a centrifugal switch after the motor is running?
Nikola Tesla
Who invented AC electricity?
True
(T/F) A method of troubleshooting a parallel circuit to find a short is to connect an ohmmeter across the main line with the power turned off.
1. Lighting 2. Volume knob 3. Television controls
3 Applications of a variable resistor
1. Commercial building lighting 2. Switch controlled outlets 3. Ceiling fan controls
3 examples of combination circuits
1. Solenoid 2. Relay 3. Motor
3 examples of electromagnetic devices
5,000,000
5Mega Ohms is equivalent to how many Ohms?
8 volts
A 12 volt series circuit has a 100Ω resistor and a 200Ω resistor. What is the voltage drop across the 200Ω resistor?
Bad
A SPST switch reads resistance of 000 while in the off position. Is the switch good or bad?
Short Circuit
A _____________ in the branch of a parallel circuit will cause excess current to flow.
Battery
A _____________ is a common source of DC current.
Short circuit
A ______________ in the branch of a parallel circuit can cause a short circuit across the power supply.
12 volts
A battery gives 12 volts to a 17Ω lamp. What voltage will it give to a 20Ω lamp?
Yes - Because 370 volts is the peak voltage rating of the capacitor.
A capacitor has a voltage rating of 370 volts. Will it work on a 208 circuit?
Equal
A capacitor in a DC circuit will charge to a voltage __________ to the source voltage.
direct short
A circuit breaker that trips immediately indicates a __________________________.
2637.6
A circuit in the US has inductance of 7 henries. What is the Inductive reactance?
40Ω
A series circuit has a 10Ω resistor, a 20Ω resistor, and a 30Ω resistor. The 20Ω resistor is shorted from one side to the other and is bypassed. What is the resistance total?
Parallel
A short circuit in a ___________ circuit can damage or destroy the power supply.
cause an excessive amount of current to flow.
A short circuit in a branch of a parallel circuit will
120 VAC (Volts Alternating Current)
A standard household wall outlet has a voltage supply of __________ volts.
Solid-state
A time-delay relay that uses an RC timing circuit is called a(n) _________________ time-delay relay
176.75 Volts
A wall outlet read 125 volts. What is the peak voltage?
Bad
A wire reads a resistance of "O.L". Is the wire good or bad?
Bad
A wire reads resistance of "I". Is the wire good or bad?
Alternating Current
AC
24 volts
According to Kirchhoff's voltage law for series circuits, if a series circuit has a resistor with a voltage drop of 5 volts and another resistor with a voltage drop of 19 volts, what is the source voltage?
ion
An atom gains an electron. What is the atom called now.
Current Flow
An inductor is a coil that opposes changes in ________________.
Circuit
Any path that allows the electrons to leave the power supply an return to the power supply is called a
Schematic diagram
Documentation that is helpful in troubleshooting a circuit.
Switch
Basic electrical component to open and close a circuit.
Off
Before "ohming" out a component, make sure the voltage is turned _______________.
isolated
Before checking continuity on a component, make sure the component is ___________________ from the rest of the circuit.
Farads
Capacitance is measured in ______________.
Farads
Capacitance is measured in _____________________.
apparent resistance to AC by a capacitor.
Capacitive reactance is
Filter out the unwanted AC voltage
Capacitors are commonly used in DC power supplies to _________________________.
Voltage Divider
Circuit that uses resistors to drop source voltage to a lower voltage
Inductor
Coil that opposes any change in current flow
Control Transformer
Commonly used to reduce line voltages of 240VAC or 480VAC to 120VAC
Parallel
Components wired in parallel in a series-parallel circuit will display characteristics of a _______________ circuit.
Amps
Current is measured in _______________________.
Direct Current
DC
Transformer
Device that transforms one AC voltage to another AC voltage
Electromotive Force
EMF
60Ω
Each light has 20Ω of resistance. What is the total resistance of this circuit.
least resistance
Electricity follows the path of ________________.
Volts
Electromotive Force is measured in _________________.
Pushbutton switch
Manually operated switch where you push a button
XLT=1/(1/XL1 + 1/XL2 + 1/XL3...)
Formula for Total Parallel Inductive Reactance
XCT=XC1 + XC2 + XC3...
Formula for calculating Total Series Capacitive Reactance.
LT=L1 + L2 + L3...
Formula for calculating Total Series Inductance
CT=C1 + C2 + C3...
Formula for calculating total parallel capacitance.
Hertz or Hz
Frequency is measured in _______________.
Rheostat
High voltage variable resistor
Divide input voltage by the turns ratio
How do you calculate the output voltage of a transformer?
1. Disconnect the power supply 2. Look for visible signs of damage 3. Connect an ohmmeter across the main line
How do you check for a short in a parallel circuit?
1. Verify primary coil continuity 2. Verify secondary coil continuity 3. Verify no continuity between primary and secondary coils 4. Verify no continuity between either coil and ground
How do you troubleshoot a transformer?
5VAC
How do you write 5 volts AC
5V or 5VDC
How do you write 5 volts DC?
127 volts
If the peak voltage in a circuit is 180 volts, what is the RMS value?
25%
If you connect a 240 volt heating element up to 208 volts, how much decrease in efficiency will you have?
Resistance will suddenly rise
If your meter is set to ohms and connected across the main line, what will happen if you disconnect the branch that contains a short?
Actual
In __________________ current flow theory electrons flow from negative to positive.
Conventional
In __________________ current flow theory electrons flow from positive to negative.
A
In a 3 phase breaker panel, what phase is the 4th breaker down on the right.
Selector switch
Manually operated switch where you select a position and turn the switch knob to it.
Insulator
Material that does not conduct electricity very well.
10 gauge
In your service van you have 12 gauge wire and 10 gauge wire. Which is the bigger gauge of wire?
DC
Inductance affects a ____________ circuit only when the current is first turned on, off, or there is a change in load resistance.
Henrys
Inductance is measured in ______________________.
No
Is a ceiling fan/lights an example of a series circuit?
Yes
Is a commercial buildings lighting systems an example of a combination circuit?
Yes
Is an electrical outlet controlled by a switch an example of a series-parallel circuit?
1/10th
It only takes _________________ of an amp to kill you.
Potentiometer
Low voltage variable resistor
Knife switch
Manually operated switch used when visual confirmation of the switch state is needed.
AC
Most of the electrical power produced in the world is _________.
It went down.
My amperage went up. What happened to my resistance?
Electrolytic, Non-Polarized, and Variable
Name 3 types of capacitors.
Actual current theory
Name the theory. Electrons flow from negative to positive.
Conventional current theory
Name the theory. Electrons flow from positive to negative.
Series Capacitance
Name this formula.
Variable resistor
Name this symbol.
Schematic diagram
Represents components with standard symbols
Ohms
Resistance is measured in ____________________.
carbon
Resistors are typically made from ____________________.
Metal
Run capacitors typically have a ____________ case.
Single pole single throw
SPST stands for
single
Start capacitors are used to start some ______________ phase motors.
Bleed Resistor
Start capacitors typically have a _________________ to drain off voltage when it is not being used.
Common
Switch contact that incoming power is connected to.
Normally open
Switch contacts which are closed when acted upon by an operator.
Normally closed
Switch contacts which are opened when acted upon by an operator.
60
The AC electricity produced in the U.S cycles ___________ times per second.
Capacitive Reactance
The apparent resistance to AC by a capacitor is called _____________________.
Primary Winding
The current load of a transformer is the current drawn by the ___________________.
Positive
The highest potential of current flow in conventional current theory is the ___________ terminal.
L
The letter that represents inductance in formulas is _____________.
10
The load resistance value in a voltage divider should be at least ___________ times greater than the resistance value of the voltage divider resistor.
Negative
The lowest potential of current flow in conventional current theory is the ___________ terminal.
an open.
The most common circuit fault is ....
Voltage
The potential difference between two points in a circuit is called ___________________.
power in = power out = loss
The power relationship on a transformer states that
Power In = Power Out + Loss
The power relationship on a transformer states that _________________________.
Inductive reactance
The resistance provided by an inductor in an AC circuit is called __________________.
True
True or false. Current flows through the neutral line when a machine is operating.
True
True or false: Nickel is a good conductor of electricity.
False
True or false: Rubber is a good conductor of electricity.
True
True or false: Silver is a good conductor of electricity.
Power Supply
To maintain a constant voltage output under varying loads requires a constant voltage ______________.
Distribution Transformer
Transformer with a center tap on the secondary
volt amperes
Transformers are usually rated in units called
Volt Amperes
Transformers are usually rated in units called _____________.
Mutual inductance
Transformers operated off the principle of ___________.
Voltage divider
Using resistors in a circuit to produce a voltage lower than the source voltage is called a ___________________ circuit.
1. Excessive current to flow 2. Damage or destruction of the power supply 3. A short circuit across the power supply
What can a short circuit in a parallel branch cause?
Thermal circuit breakers
What do the symbols on the right side of this disconnect represent?
The rest of the circuit to operate with a reduced current
What does an open in a branch of a parallel circuit cause?
micro
What does the symbol µ represent?
60 Hertz
What is the Hertz in the United States?
3.6 amps per phase
What is the amperage draw per phase on a 240 volt 3-phase 1500 watt motor?
12 gauge wire
You are pulling a new circuit that connects to a 20 amp breaker. What size of wire do you need?
10 gauge
You are pulling a new circuit that connects to a 30 amp breaker. What size of wire do you need?
open.
You have an ohmmeter connected across the main line of a parallel circuit. You disconnect one branch and there is no change in ohms. You have discovered the branch with a(n)
AC or Alternating
_____________ current flows alternately in one direction and then the other.
Current
______________ delivers electrical power to its point of use.
Electricity
___________________ is the flow of electrons in a conductor.
Direct Current
______________________ electricity flows in only one direction.
