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46 Cards in this Set
- Front
- Back
Voltage is electric pressure. It is similar to psi in a gas line. What is the scientific name for voltage and what letter is used to identify it? |
Electromotive Force E |
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Amperage is the flow of electrons. It is similar to gallons per minute or litres per second of flow in a pipe. What is another word to describe amperage and what letter is used to identify it? |
Induced current I |
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An Ohm is the resistance of a wire or circuit to flow. What happens when there is a higher resistance to flow? What letter identifies resistance in Ohms? |
Less flow R |
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Ohms law paradigm |
E I. R |
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In Watts Law, Volt Amps = Watts( W) or Power Voltage = E or V Amperage equals I or A. There are two watts different ways to identify a Watts Law paradigm. Remember, Watts was a baker |
W (watts). A( Amps) V ( voltage) Or P ( Power) I ( Amps) E ( voltage) |
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Watts Law states that apparent power (P)is equal to voltage X amperage. P = V X A Voltage x Amperage = VA ( volt amps) The Maximum Amperage can be determined by dividing the VA rating by the voltage supplied to the circuit. If a 24 volt transformer has a rating of 40 VA, what is the maximum output in amps? |
40va / 24v = 1.6 Amps |
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The 3 devices needed to make a circuit are ? |
A power source A switch A load ( consumer) |
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A volt meter will display the difference between 2 leads If the voltage in the read lead is 24 and the voltage on the black is 0 , what will the meter display? |
24 |
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How must a volt meter be connected? |
In parallel with the power on |
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The Ohm meter will display the resistance of the circuit in OHMS. How must it be connected? |
In parallel with the power off Leaving the power on may damage the meter. |
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An amp meter will display the amount of current flowing through a circuit or device. How must an amp meter be connected? |
In series with the power on. |
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A clamp on an ammeter is connected by clamping around one wire . What will it read if you clamp around two wires? |
It will read zero |
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If the amperage reading is too low to attain a proper reading, what must be done? |
Wrap the wire 10 times and insert into the jaws of the meter. Then take the reading and divide it by 10 |
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What does a continuity test prove? |
The existence of an electrical pathway |
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When you are unsure of the voltage, amperage or resistance, where do you set the meter? |
On the highest setting , it can then be lowered |
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Why does a digital meter flash OL? |
The meter scale has been exceeded and we need to use a higher scale. |
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What two types of current are used on gas appliances? |
AC ( alternating current ) and DC ( direct current) |
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When using a DC meter, where must the Red lead be connected? |
On the positive terminal. AC power is not polarity sensitive |
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A series circuit has one current pathway, a parallel circuit has two or more independent current pathways . What are series/parallel and Series AND parallel circuits? |
Series/parallel the series portion controls the parallel portion Seres and parallel the two circuits are independent of each other. |
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This formula is for calculating the resistance of what circuit? Rt= R1 + R2 + R3 |
Series circuit |
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What is the formula for calculating resistance in a parallel circuit? |
1/Rt= 1/R1 + 1/R2 +1/R3 |
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The total resistance of a series/parallel and a series AND parallel circuit is found by________ |
Combining both formulas |
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The total resistance of a series circuit will always be ______than the _______ resistor in the circuit. |
Higher Highest |
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The total resistance in a parallel circuit will always be ________ than the ________ resistor in the circuit. |
Lower Lowest |
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Kirchoffs amperage law states that the total amperage draw will always be what? |
The sum of the amperage draws through each leg of the circuit |
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All wiring diagrams accompanying gas appliances are shown with the unit in ______ |
Stand By |
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Which type of diagram uses symbols and shows the rough geographic location of the controls and actual wiring as it appears in the appliance? |
Connection |
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Which is the best diagram for trouble shooting? |
A ladder diagram. It uses symbols and shows how the unit works |
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______ are wired into the circuit in series so that any one ______ Can shut off the system. ________ are not consumers. |
Switches Switch Switches |
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Power consumers consume power and must be wired in parallel. What are 2 examples of power consumers? |
Gas valves and motors ( loads) |
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The potential difference ( voltage) across an open switch ( off) would be equal to the voltage supplied to the circuit. What would the potential difference in voltage be across an difference across an energized switch ( on) be? |
Zero |
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What does a heat anticipator in a room thermostat do? |
Causes the switching mechanism to respond quicker , shutting off the forced air furnace to reduce or eliminate temperature overshoot. |
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How does a diaphragm gas valve open or close? |
Gas pressure. It is slow to respond |
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A solenoid gas valve reacts to a call from the operating control . How fast does it respond ? |
Immediately |
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A solenoid gas valve acts on magnetism. When the coil is energized it is energized by ______. |
A strong electro magnet that lifts the valve off its seat. An iron core is inserted into the coil to concentrate and intensify the magnetic field. |
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A step down transformer is both a power consumer and power source.the primary coil is ______and consumes power. The secondary coil is ______ and is a power source. |
110 VAC 24 VAC |
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How is electromotive force measured? |
Volts |
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How is resistance measured |
Ohms |
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How is electrical power measured? |
Watts ( P) |
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What material is the best conductor? |
Copper |
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What is the amp draw on a 120volt 60 watt lightbulb? |
P( 60 watts) I ? E ( 120 Volts) 60/120 = 0.5 Amps
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How many loads in a series circuit for a gas fired appliance? |
1 |
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Why are parallel circuits used in the heating industry? |
To supply the same voltage to the loads |
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What is the voltage supplied to four parallel circuits with a 120v power supply? |
120 volts |
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What is the maximum high limit setting for a forced air conversion furnace? |
250F |
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What will a poor ground in an ignition module cause? |
No main flame |