[D2L] Final Review Flashcards
What is the term for electrical charge at rest?
Electrostatic
What is required to form a magnetic domain (all atoms become aligned resulting in magnetism in one direction)?
Magnetic moments
How many electrons in a coulomb
6.28 x 10 exponent 18
one volt is the value of the difference in charge that will cause a current of one ampere to flow in a circuit with a resistance of one ohm
True
What affects the ability of a conductor to transmit an electrical current?
a) Cross-sectional area
b) Length
c) Diameter
d) All of the above
All of the above
What are the 4 components of a practical electrical circuit? (what is required for a proper circuit)
Source of emf, conductors, switch, load
To calculate the Emax value of a sine wave, Divide the RMS value by the ( ) or Multiply RMS by ( ).
Sine of 45°, √2 (square root 2)
Determine the instantaneous voltage at 30° if an ac voltmeter reads 110v
78v
(AC voltmeter = RMS)
Which of the statements are true?
a) Voltage has the same charge between two points
b) Voltage is measured across a device, between two separate points along two different conductors
c) Voltage can be defined as a balance of electron distribution
d) Voltage is the measurement of difference in charge between 2 poles
Voltage is the measurement of difference in charge between 2 poles
An (emf) electromotive force maintains the difference in charge
True
What is the symbol for electrical Charge?
Q
There are six methods for producing an emf. Pick 2 source names that ARE NOT methods. (MULTISELECT)
a) Light
b) Heat
c) Electrical
d) Pressure
e) Radiant
f) Chemical
Electrical
Radiant
Using a “CAT-l” electrical meter device, you can test utility connections and power lines?
False, CAT 3 & 4
Which one is incorrect?
a) Never use an ohmmeter on a energized circuit.
b) Clamp around only one wire when using an ammeter
c) If the display meter is flashing on and off, the measurement is greater than the range overload setting on the meter
d) When checking polarity on an AC circuit, Red goes to hot, Black goes to Negative
When checking polarity on an AC circuit, Red goes to hot, Black goes to Negative
In an Capacitive circuit, Current leads Voltage by 90 degrees?
True (ICE)
????If the instantaneous voltage is 10V at 110 degrees, what would voltmeter read?
7.937
A lock that you use to lock out equipment can have more then one key?
False, only one
what amount of electrical current can cause heart failure or death?
100mA to 200mA
A Transformer is a…..
Series of windings used to step up/down voltage
Inductance is the opposition of
Change in Current
what is the positive plate called on a battery? (hint: the negative plate has an “n” in the word”)
Cathode (Positive)
Anode (Negative)
Thermocouples use heat to generate Electricity?
True
What is Faraday’s law?
States that the magnitude of an induced voltage of a conductor is proportional to the rate that it cuts the lines of flux from a magnet.
A conductor moving parallel to lines of magnetic forces produce:
Minimum emf
what does increasing the current in a coil do to the EMF
increase the EMF
the number of turns on the primary and secondary coils determines the amount of the mutually induced secondary coil voltage.
True
Gas burners can have built-in _______ ignition system. (think BBQ)
piezo-based
What is the order of the 7 steps normally used in a lockout procedure? (Drop down selection)
- Notification
- Shutdown
- System Shutdown
- Lockout
- Tag
- Recheck
- Re-energize
What are the steps for preforming an operational test of an ohm meter before you check for a voltage in an unknown circuit? (Multi select)
a) Check meter to a known voltage
b) Check the circuit
c) If it shows de-energized, check meter to a known voltage source again
d) Check polarity of circuit
e) Make sure the power source is on and stable
a) Check meter to a known voltage
b) Check the circuit
c) If it shows de-energized, check meter to a known voltage source again
If the amperage reading is lower then your clamp-on ammeter’s capability, you can loop the single conductor through the clamp to take a reading.
True
Polarity is NOT a factor when using an ohmmeter.
True
Polarity is NOT important when measuring ac currents.
True
which of the following factors determine the extent of injury a current will have on the body? (Multi select, pick 4)
a) A persons skin resistance
b) Improper grounding
c) Size of the area of contact
d) Which part of the body is in contact
e) puddles on the ground
f) how much pressure is applied
a) A persons skin resistance
c) Size of the area of contact
d) Which part of the body is in contact
f) how much pressure is applied
what is the voltage rating for Class 0 (red) electrical rubber gloves?
up to 1,000 V
One alternation occurs within 180 degrees of an electrical sine wave
True, 360 is a cycle
The time required for one alternation to complete is also known as a period.
False
One cycle is one positive alternation and one negative alternation
True
When a 4 pole alternator turns 1500r/min the output frequency is 60hz
False, it’s 50Hz
Three phase wires are White, Black, and Blue?
T or F
False
Phase A: black
Phase B: red
Phase C: blue
Fuse rating can not be greater than 125% of the smallest wire or component in the circuit
True
Single conductors may have a max load of 80% of the rated 15A
True
Arc flash can be caused by environmental, aging material and worker interaction. Which of these is not a likely concern
a) Condensation
b) Dust on circuits
c) Resetting a circuit breaker
d) Current in mA
Current in mA
Fuses allow 3x their rated current for a few seconds for surging of motors
True
What is flux density?
The number of lines of force passing through a unit area of material
What are some examples of Ferromagnetic materials? (MULTI-SELECT)
Iron
Wood
Nickel
Cobalt
Glass
Iron
Nickel
Glass
What pole do flux lines leave and then enter?
Leave through the north and enter through the south
What is a Megohmmeter (Meggar) used for?
Checking Wire Insulation
If a wire is shorted out
If a wire is burnt open
Just think of it as an open switch(not there)
not functionable, no current can flow
GFCI(Ground Fault Circuit Interrupter) detects leakage as low as 3-5mA (0.003-0.005A)
True
