Electrical Flashcards
The “law of electrical charge” is …
Opposite charges attract each other; like charges repel each other
electrical current (or flow of electrons) in a wire may cause
- Friction, and therefore heat
- Opposite electrical charge to be induced in another material
- A magnetic field around the wire
Materials that easily conduct electricity are called
Conductors
Materials that do not easily conduct electricity are called
Insulators
T or F
electricity will flow freely through a closed switch
T
electromotive force, or EMF is another term for …
voltage
an ampere is a unit of measurement for …
Electrical current
Electrical current is measured in
Amps
electrical potential is measured in:
Volts
Electrical resistance is measured in
Ohms
when checking to determine an unknown supply voltage with an analogue metre having ranges of 0-50 v, 0 - 200 V, 0 - 600 V, and 0 - 1000 V, which range should be selected?
0 - 1000v
Which metre is used to check for electrical potential?
Volt Meter
which metre is used to check for electrical continuity ?
Ohm metre
when checking an electrical circuit with an ohm meter, a reading of “OL” or “ infinity symbol oo” indicates
Open circuit
T or F
Test leads must be disconnected when changing the function select dial
T
T or F
No. 14 AWG electrical wire is thicker than NO. 16 electrical wire, and can carry more electrical current safely.
T
what insulator colour would be used for a ground wire?
Green or bear
What insulator colour would be used for the L2 (neutral) wire?
White or gray
what insulator colour would be used for L1 (source or hot ) wire?
Black, red, blue, yellow
The ohm metre reading across a good fuse that has been removed from the circuit, will be …
0 ohms
The ohmmeter reading across a blown fuse that is removed from the circuit, will be …
infinity
A badly burned or charred fuse indicates
A short circuit
T or F
A voltage drop never occurs across a switch
F
The line connection terminals on a 120 V receptacle are
A) Gold
B) Green
C) Silver
D) Black
A) Gold
The neutral connection terminals on a 120 V receptacle are
a) green
b) gold
c) silver
d) black
c) silver
Ohms law states …
it takes one Volt to push one Amp through one Ohm
if voltage is increased in a simple circuit, current will
Increase
Given a constant supply voltage, if resistance increases in a simple circuit, current will …
Decrease
Electrical power is measured in units of what
Watts
One horsepower of mechanical power is equal to _______ watts of electrical power
a) 24
b) 56
c) 746
d) 1346
c) 746
Which of the following changes to an electrical current will increase power delivery to the load
A, current can be increased
B, resistance can be decreased
C, voltage can be increased
D, all of the above
D, all of the above
One Watt is equals ______ Btuh
3.41
what is the BTU output of an electric heater rated at 20 kW
68,240
T of F
If one load fails in a series circuit, then all loads will stop operating
T
with constant supply voltage, what will be the effect on total current if the resistance is decreased in any one branch circuit of a parallel circuit?
Amperage will increase
The amperage rating, at any point in a parallel circuit will be
Different on the main line, compared to each branch line
If the voltage drop across a load in a simple circuit is not the applied voltage, this indicates
There is more than one load wired in series with the tested load
The equivalent resistance of 20w resistors connected in parallel is
10w
The equivalent resistance of two 20w resistors connected in series is
40w
total resistance (Rt) in a series circuit is equal to
a) supply amperage
b) supply voltage
c) some of each individual resistance in a circuit
d) the true RMS reading
c) some of each individual resistance in a circuit
in North America, AC power is produced at a frequency of _____ cycles per second (also_____ hertz)
60
back EMF is an electrical term that means
Induced voltage from the coil of an inducer that opposes applied voltage
(wires are too close together and create a magnetic field)
An ohmmeter reading across the wires on a good induction coil will indicate
a) infinite resistance
b) measurable resistance
c) zero resistance
d) fluctuating resistance
b) Measurable resistance
an ohmmeter reading between a good solenoid coil, and the solenoid casing will indicate
a) infinite resistance
b) measurable resistance
c) zero resistance
d) fluctuating resistance
a) infinite resistance
T or F
The current draw of an electric motor is constant from start to finish
F
(draws more at the start)
If there are more turns of wire on the primary windings of a transformer, then on the secondary winding, the transformer is called a
Step down transformer
ignition transformers are Step- ____ transformers
Step-up
Transformers which produce a secondary voltage that is higher than the primary voltage are called
step-up transformers
How far into a junction box must conductors extend
6”
Which class of fire extinguisher should be used to extinguish an electrical fire?
Class C
what device converts DC to AC
Inverter
what device has a capacitor connected to it
Blower Motor
The 24V control circuit supply on a residential furnace comes from a
30/24v step down
240/24v step down
120/24v step down
240/24v step up
120/24v step down
an infinity or OL ohm metre reading taken across two disconnected wires of a solenoid relay coil indicate that …
a) The coil is good
b) The coil wire is broken
c) The coil wire is shorted to the casing off the device
d) all of the above
b) coil wire is broken
when using an ammeter, that is not “clamp on” type a metre to measure current, how must the ammeter be connected into the circuit?
a) in parallel with the circuit, with the circuit de energized
b) in parallel with the circuit, with the circuit energized
c) in series with the circuit, with the circuit de energized
d) in the series with the circuit, with the circuit energized
d) in the series with the circuit, with the circuit energized
if your metre is set to measure voltage and you have it across a closed switch on a 120 vac circuit, the reading should be?
a) 0 whether the circuit is energized or not
b) 120 if the circuit is de energized
c) 120 if at least one leg of the circuit is energized
d) 24 if the circuit is energized
a) 0 whether the circuit is energized or not
if your metre is set to measure voltage and you have it across an open switch on a 120 VAC circuit, the reading should be?
a) 0 whether the circuit is energized or not
b) 120 if the circuit is de energized
c) 120 if at least one leg of the circuit is energized
d) 24 if the circuit is energized
c) 120 if at least one leg of the circuit is energized
What Is the Device that converts AC to DC
Rectifier
the VA rating on a transformer indicates :
a) the available power to the primary circuit
b) the available power to the secondary circuit
c) the transformer uses “varying amperage”
d) the transformer can only use dc power
b) the available power to the secondary circuit
Ohmmeter reading across a good coil will indicate
a) infinite resistance
b) zero resistance
c) measurable resistance
c) measurable resistance
a millivolt is expressed as
a) 1000v
b) 100v
c) 1/100v
d) 1/1000v
d) 1/1000v
14-2 wire contains :
1-black, 1-white, 1-bare, 14 AWG conductors
