Current is constant thru a series.
Atoms are made up of a nucleus of protons and neutrons and shells of electrons orbiting around the nucleus.
Lithium atom--
The difference between positive and negatively charged atoms :
Negative have and excess of electrons
Positive are missing an electron (have and extra proton)
Nature abhors an excess, it wants balance. Therefore, there is a natural flow from the excess to the depleted.
Voltage: measure of the potential difference between two points. [w/q; work per charge; actually a measure of energy]
Let's use water as an analogy for electricity. Almost everything that electricity can do can be done with water. That field is called Fluidics. We'll use water to help us understand how electricity flows.
Voltage is the pressure behind the flow of electrons. Just as your house water has 30-60 psi of pressure pushing it out of the faucet, electricity has a voltage that pushes it along.
Voltage is measured in volts or millivolts. The abbreviation is v or mv.
Current: measure of how fast the electrons are flowing. Water analogy is how fast the water is flowing thru the pipe. Current is measured in amps or milliamps. The abbreviation for amps is a; for milliamps is ma. A gallon of electrons is called a Coulomb = 6.24 1024 electrons. 1 amp = 1 coulomb per second.
Resistance: measure of the restriction which governs the flow. Resistance is measured in ohms or kilo-ohms. [Kilo is Latin for 1000] The abbreviation for ohms is the Greek letter omega, . Use k in front of the for values higher than 1000.
Resistance is determined by:
1. # of carriers in a material. Conductors have lots of free electrons. Resistors have more stable outer levels, need more to dislodge an electron.
2. Length of the conductor.
3. Cross sectional area (dia)
4. Temperature - higher the temp. the more random motion of electrons, so more resistance or more energy spent to move an electron in the direction you want it to go.
MUST SHOW UNITS AT ALL TIMES!
Voltage -- Show two decimal places at all times.
Amperage -- If amperage is less than .1a, show as ma to zero decimal places. Otherwise, show to two decimal places.
Resistance -- Above 1000 , show as k. to zero decimal places.
Sources of Electricity
(Sources to produce a voltage)
Converts solar energy directly to electrical energy
Voltage is based on the difference between the two materials levels on the donor scale.
Current is the rate of the chemical reaction. D, C, AA, AAA are all 1.5 volts. Their difference is in their capacities (ampacity)
Piezo-electric. When the item is physically distorted, one side gives, the other receives electrons causing a current to flow. Used for pilotless ignition for gas appliances. A sharp shock creates a high voltages. The voltage makes a spark. Same method for outdoor gas grills.
This phenomenon also works in reverse. Piezo-electric speakers use an electric current to cause mechanical motion of the speaker.
This is how a power plant works to make the electricity we use. A conductor moving thru a magnetic field causes a current to flow.
Faraday's law - voltage is dependent on
1. # free electrons relative to the amount of wire (how good a conductor is it)
2. Magnetic field strength.
3. Rate of flux cut (movement of conductor thru the field)
Circuits composed of a number of resistors can be reduced to one Composite Resistance,
All resistors are in line.
Current is constant thru a series.
Voltage is constant across each component of a parallel circuit.
When in doubt, write the equation for each component and fill in the blanks.