Chapter 2 Notes - Posted on 2016-11-23 by Nicholas Casas

Chapter 2 Notes

• All matter is composed of atoms
• Bohr Model: Electrons circle the nucleus, which is composed of protons and neutrons.
• Protons=+
• Electrons=-
• Neutrons are neutral
• If the atom has the same number of protons and electrons it is considered stable.
• Atoms with less electrons are positively charged and vice versa.
• The constant flow of positive/negatively charged atoms finding pairs creates electricity.
• The total attraction between positive and negative groups is called a Charge.
• Electrons are passed from atom to atom in a wire which creates an electrical current.
• Elements that have loose electrons orbiting around the nucleus are said to be better conductors of electricity. Silver, Gold, and Copper are all great conductors of electricity.
• Insulators: Elements composed of atoms with tight orbiting electrons. Rubber, Plastic, and Glass are some of the best insulators.
• Resistance varies in a wire based on its thickness, length and material. Gauge: The density of the wire. -Guage=+Wire
• Copper is a popular conductor for it's the cheapest
• Resistance: The opposition of flow to an electrical current. Measured in Ohms (Omega Symbol).
• Resistance to flow to electricity causes friction, which displaces energy in the form of heat.
• Hair dryers and car cigarette lighters produce heat by controlling the resistance of an electrical flow
• Voltage: The measurement of electromotive force. +Pressure=+Voltage.
• Voltage is not an absolute measurement. It is a difference in electrical potential.
• Current, measured in Amperes, is the speed of flow. It is dependent on the voltage/resistance of an electrical circuit, but only to some extent. An Ampere is the amount of electric charge passing a point in an electric circuit per unit of time.
• III Primary measurements of electricity: are Voltage(V), Current (I), and Resistance (R).
• Ohm's Law: Voltage= CurrentXResistance (V=IR) Current= Voltage/Resistance (I=V/R) Resistance= Voltage/Current (R=V/I)
• Circuit: Circular line, route, or movement that starts and finishes at the same place.
• Circuit (Bridge): The bridge between the negative and positive area. Depending on the resistance of the material creating the circuit, the electrons try to move as fast as possible.
• Short Circuit: When There isn't enough resistance and too many electrons cross over in too little of time. This destroys the bridge by the heat that friction has produced.
• Most circuits today are conductive material laid out on printed circuit board (PCB). Components are soldered on a PCB and connected to each other through conductive material etched onto the circuit board itself.
• Analog circuit is a circuit that carries a voltage that is either continuous or changing. There are two categories for analog circuits; series and parallel. Series circuit: If one circuit is broken, then the rest of them go out as well. Parallel Circuit: An equal amount of voltage is distributed to the components due to how these components are wired. Therefore, if one fails, then the rest still work.
• Digital Circuit: Transmits binary values in the form of an on or off signal. It can handle complex information based on its use of: 1=positive voltage and 0= zero voltage.
• Alternating Current (AC): Changes in electrical flow in both directions, changing 50-60 times per second. U.S. Voltage Standard=120V;60 Cycles per second. In Europe it is 220V;50 cycles per second.
• Thermal, Nuclear, and fossil fuel energy all produce AC at around 25,000 volts. Electricity loses energy over time. Long distance electricity must be done at high voltage. Step-up Transformers take the 25,000 volts and bring it up to sometimes 400,000 volts.
• One Transformer can handle voltage for up to four homes.