Basic Electronics
Terms
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- What is the definition of electric current?
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the movement of free electrons from one point in a conductor to another.
the movement is due to the influence of a difference of potential existing across the conductor. - What are the 3 fundamental elements of Electric Current?
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1. Voltage
2. Current
3. Resistance - What is another name for voltage?
- Electromotive force
- what is the definition of Voltage?
- the difference in potential energy existing between two points in a conductor due to an unbalance electron population at these points.
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What are the names of the unbalanced points of electron population that give rise to voltage?
what are the populations in magnitude? -
Negative and Positive poles.
Negative = electron excess - lots
Positive = electron deficiency - none - What is the direction of voltage flow in a circuit?
- From negative pole (e- excess) to positive pole (e- deficiency).
- What is the unit of measurement for voltage?
- Volts
- What is the definition of current?
- movement of electrons in a conductor
- what is power?
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Current x Voltage
P = IV - What is a fuse?
- a heat dissipator - when the instrument current gets too high, it melts and prevents damage. Wattage rating shows how much heat it can take.
- what type of division do you use to divide current in a circuit?
- parallel
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How do you divide voltage?
How do you divide current? -
Voltage: resistors in series.
Current: resistors in parallel. - How many components are in an instrument? What are they?
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6 - SIX - 6
-Power supply
-Modifier
-Light detector
-Display
-Microprocessor - What are 4 types of Power modifiers?
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-Capacitors
-Transistors
-Amplifiers
-Transformers - what is a Capacitor?
- it stores electrical charge. When the switch is open, no charge; when closed, charge builds up across dielectric space.
- What is a Transistor?
- a semiconuctive device with an emittor and a collector, housed on a very thin semi-conductive material. Emits electrons as current.
- what is a transformer?
- a power supply modifier that increases or decreases the power intensity based on its size.
- what is a diode?
- a type of power modifier that convers AC to DC.
- What is the only way a diode will work?
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If the anode is Pos and
if the cathode is Neg. - What is a Rectifier?
- a diode that is used to convert AC to DC
- What are 5 types of light detectors?
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-Photovoltaic
-Phototube
-Photomultiplier tube
-Phototransistor
-Photoconductive cell -
What is a Photovoltaic?
-does it need power? -
a light detecting device.
no, needs no external power supply. - Why not use a photovoltaic?
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-wears out fast
-needs long periods of light
-temperature causes inaccurate signals. - what is a phototube?
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like a photovoltaic cell
-needs a constant power supply
-needs power modified to DC.
-needs amplification. - What is a photomultiplier tube?
- a phototube with internal amplification.
- what is a phototransistor?
- a light detector like a phototube, only it has a lens that focuses light onto the electric sensitive material.
- what is a phototransistor used for?
- barcode readers.
- what is a Photocunductive cell?
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A very small light detector
-uses Cadmium sulfide
-resistance decreases as it's exposed to light. - what is a photoconductive cell used for?
- In the flame photometer, it turns a light on when the flame is on so you don't have to peer down at it.
- what are 3 types of display systems?
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-Analog
-Digital
-Cathode ray tube. - what are 2 types of analog display?
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-Direct (D'arsonval)
-Null balance (Wheatstone) - what are two types of Direct Analog displays?
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-Galvanometer
-Meter - what concept is d'arsonval movement based on?
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a sensing coil senses current from a permanent magnet;
Galvanometer: makes mirror flash
Meter: makes coil w/ attached pointer align with mag field. - What is Wheatstone null balance detection based on?
- -2 fixed resistors, a POT, and an input transducor hooked up in parallel. By calibrating at zero, when a measurement is made it will cause the meter to deflect.
- What are 2 types of Digital display?
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-Electromechanical
-Electronic - what type of digital display is an oscillope
- electromechanical
- what emits light in electronic digital displays?
- glow tubes or Diodes.
- what is a microproccesor?
- semicundor that does math, logic, and makes decisions under stored control instructions.