Electrical Flashcards
What charges do the following have?
Electrons
Protons
Neutrons
Electrons = negative charge
Protons = Positive charge
Neutrons = No charge
What are the magnet rules that govern their operations?
- have 2 poles: north + south poles (Like repel, unlike attract)
- Magnetic lines (flux lines) continuous + always form loops
- Magnetic lines of force never cross
- Magnetic lines form tight loops which act like rubber bands, constricting / forcing 2 magnets to become one
True or False: There’s insulation for magnetic lines of force
False: There is no insulation against magnetic lines of force
What happens if you move a conductor through a magnetic field or a magnet through a coiled conductor?
The moving magnetic field will induce a voltage potential.
(the faster the magnet moves = stronger the voltage)
AC generates what?
electromagnetism
Magnetism produces what type of current?
AC
What does EMF mean?
How is it meansure?
Electromotive Force
in Volts
What is thermoelectric effect?
Happens when heat is applied to two dissimilar metals
What is a thermocouple?
Is made of 2 dissimilar metals welded together at the tip.
How does a thermocouple work-ish?
When electromagnetic is charged, it holds a valve in the open position / allows gas to flow to appliance
In North America what is the frequency at which electricity flows?
60 hertz (Hz)
What is an electrolyte?
It is a liquid or paste where a chemical reaction takes place.
What is Piezoelectricity?
It is pressure causing an electrical charge.
Ex: Spark igniter used to light a gas BBQ
What is the only source of electricity that produces AC?
Magnetism
What is the term given to 6.28 quintillion electrons?
A coulomb of charge
What are the 4 basic components of an electrical circuit?
Source
Conductor
Switch
Load
The larger the hose, the …..
The higher the flow rate.
Bigger hose = bigger flow rate
Just remember Gallons / min + L / sec
What does Ohms measure?
Resistance to the flow of current
What are the 3 variations that Ohm’s law?
- E = I x R
- R = E / I
- I = E / R
E = EMF (Volts)
I = Current or Flow (amps)
R = Resistance (Ohms)
Ohm’s Law states what?
It takes 1 volt to push 1 amp through 1 ohm of resistance
(1 volt -→ 1 amp -→ 1 ohm)
A useful tool to asses a circuit / find an unknown valve
Work performed by the load is described by what?
Power / measured in Watts
What is Watts?
How is it expressed?
Watts is the product of voltage / amperage
- P = E / I
- E = P / I
- I = P / E
DC electrons flow through conductors which way?
Negative terminal -→ positive terminal
What is the 4 basic components of a Simple Circuit?
(P - C - S - L)
- Power source of voltage potential
- Conductors to provide a path for current to flow
- A Control (aka Switch)
- A Load with resistance to perform work.
What are the colours of the 2 hot wires?
Red and Black
2 breakers combined together is what?
Double Pole, Single Throw (DPST)
What is this image?
Double Pole Single Throw
Where should disconnect switches be placed?
Always placed in the “hot” leg of a circuit
How does an overload occur?
whenever there is too much current for the size of the wire.
Happens when too many loads are plugged into the same circuit.
DT being wired parallel to each other the amperage would increase / cause overheating of conductors
Again, how does an overload occur?
If a current in a circuit increases it’s because to many wires are wired in parallel to each other.
What are the designs that are built to withstand the initial current load caused by the starting of electric motors?
Time - delayed fuses
What is the advantage of circuit breakers over fuses?
Breakers can be reset whereas fuses must be replaced.
Breakers are recyclable
What happens when excessive current flows through a thermal device within breaker?
The thermal device (a bimetal element) will warp when it gets too hot and “trips” the breaker / opens the circuit.
In a Series Circuit, if one of the three light bulbs in removed, what happens?
The path or circuit is broken and none of the bulbs will light.
True or False: the total resistance in a series circuit will be the sum of all individual resistances in the circuit.
True
Rules for Series circuit, GO
- Total resistance = individual sum of resistances
- Amp / current is the constant
- Kirchhoff’s Law: total voltage = sum of voltage across individual loads
A circuit that has more than two paths to follow
Is a parallel circuit
The total resistance of a parallel circuit is always…..
less than the resistance of the smallest of the individual resistances
Total is less than the smallest number…
Rules for a Parallel Circuit, GO
- Voltage is the same throughout
- Use the triangle to find amperage..
- The sum is less than the smallest resistance number
A transformer acts as both of…
A source and a load
Primary side: load
Secondary side: source
Electrical energy is transferred through transformers how?
By magnetic induction
How does an electromagnet (aka solenoid) work?
- Coil is electrically energized / current flows through
- intensified magnetic field of coil pulls iron rod into centre of coil
- Iron rod stays in this position until coil in de-energized
Relays are used in hydronic heating / air conditioning how?
120 V or 240 V motors are switched on / off by a 24V control circuit
Relays can be both what?
A load and a switch
Load on the 24 V side
Switch on the 120 V or 240 V side
What is the term given to a coil of wire into which an iron armature is drawn?
a solenoid
What is this?
Temperature Switch
Opens a circuit on a rise in temp
What is this?
Pressure Switch
Closes a circuit on a rise in pressure
What is this?
Transformer
They increase or decrease voltage bn primary / secondary circuits.
What is this?
Fuse
Opens a circuit when too much current flows
What is this?
Ground
A connection to the earth that has no voltage potential
When working on electrical equipment that is live, how many hands do you want on the live equipment?
Only one hand, current will probably flow through the hand and down through the feet.
Two hands: electrical path would be through the heart
