CVT 102 Lecture Electicity Flashcards
The difference between electrons, newtrons, and protons
The outer shell is a cloud of potential
Static Electricity
Electrons are not moving and sitting on a surface.
when you walk across a rug and you get shocked.
Cathode and Anode
Cathode is Positive of your AA battery
Anode is negative
Positive to positive repels
negative to negative repels
positive to negative attracts
Electricity
- physical phenomenon
- Attraction of particles with opposite charges
- Repulsion of particles with some charge
Electrons (-)
Protons (+)
Neutrons (No charge)
How do you measure I(Ampere) in Series Circuit?
V
I=——
Rt
You take the voltage from the battery and you divide it by the total resistance
Ohms Law V(E)
_________
I | R
This is the equation used to get resistance, voltage in volts and current in A (Amps)
OHMS LAW!!!
Resistance in Series Circuits
- You add resistance in Series together
- Resistance is in Ohms Ω
Rt = R1 + R2 + R3….
Ohm
Named after the German man
George Simon Ohm
Symbol R
unit of abrev Ω
unit of measure Ohm
Physical phenomenon
The behavior of electrons
Caused by the attraction of particles with opposite charges and the repulsion of particles with the same charge
Electrons: (–) charge
Protons: (+) charge
Neutron: no charge
What are the charges for each?
Electrons:
Protons:
Neutron:
Electrons: (–) charge
Protons: (+) charge
Neutron: no charge
Electrons (loose ones) can rest on?
Can rest on a surface
Electrons can be forced out of
Can be forced out of orbit
Electrons can move through
Can move through:
Metal
Gas
Vacuum
Near the speed of light
(186,000 miles/sec)Electrons cause
Friction, light, heat,
or chemical reaction
Electrons create
Creates an ion and a “free”
negatively charged electron
Electron Flow
In a simple circuit,
(Compare to the flow of water through pipes)
electrons flow through wires and electronic components
Conductor:
Allows the flow of electrons. The outer valence layer is not full, allowing electron movement. Includes metals, impure water, plasma gases.
Insulator:
Impedes the free flow of electrons. The outer valance band is full, impeding electron movement. Includes glass, rubber, plastic, ceramic, pure water, wood. (Caution! Why? Could have moisture…)
Direct Current (DC)
Electron flow is one-way
Typically from wet- or dry-cell batteries or power supply
Thermoelectric in advanced circuitry
Let’s talk about cells and batteries . . .
Why are batteries DC current?
Batteries
Contain electrolytes: ionic solution
2 dissimilar metal plates, or poles
Connected by a conductor,
electrons (& ions) move
Electrolyte in solution is a wet cell,
like a car battery
Electrolyte in a paste is a dry cell,
like a “AA” batteryThe point of any voltage source?
To encourage electrons to move:electromotive force.
Alternating Current (AC)
Alternating Current (AC)
The current actually reverses direction repeatedly (because the polarity reverses).
Here in the US, the current makes a complete cycle 60 times a second.
The units for cycles per second: hertz (Hz).
Alternating Current (AC) Commercial Power Generation
Commercial Power Generation Transmitted over high-power lines at 110-230 Kilovolts Transformers step down power for retail customers
Rotate a metal coil within a magnetic field
Electrons are induced to flow
(electromagnetic induction)
Does not degrade over long distances
Can be used in a transformer (step up or down)
Many ways to spin the coil—coal, gas, nuclear, hydro, geothermal, solar, wind, tidal,
waste-to-energy)
What about free electrons that aren’t moving?
Not moving: static. Some conditions (e.g., dry weather) promote separation of charge, collections of electrons. This is why you’re afraid to touch the car door in Santa Ana weather conditions. Common demonstration: brush hair with a comb, then watch it attract particles. Why? The particles (some of them) have positive charge, the comb negative, so they attract.
