Principles of Electricity Background to electricity, circuits, and how to calculate

Parts of the Atom Electrons – negatively charged particles that revolve around the nucleus of the atom. Electrons – negatively charged particles that revolve around the nucleus of the atom. Protons – Positively charged particles that revolve around the nucleus of the atom. Protons – Positively charged particles that revolve around the nucleus of the atom. Neutrons – No charge in the atom. Neutrons – No charge in the atom. -These parts are important to know because they determine the charge of the atom. -The charge of the atom creates the energy used as electricity.

Parts of a Circuit Consists of 4 Parts Consists of 4 Parts - Source - Conductors - The Load -Control Device

1 - Source Source – Produces the force that causes electrons to move. Source – Produces the force that causes electrons to move. Think of a water source that pushes water through a pipe. Same principle. Think of a water source that pushes water through a pipe. Same principle. Electrons (-) are attracted by positive charges, and repelled by negative charges. (Opposite charges attract each other.) Electrons (-) are attracted by positive charges, and repelled by negative charges. (Opposite charges attract each other.)

2 - Conductor or Path Conductors – Provide an easy path for electrons to move throughout the circuit. Conductors – Provide an easy path for electrons to move throughout the circuit. Copper is the most commonly used conductor in electronics and residential wiring. Copper is the most commonly used conductor in electronics and residential wiring. Other conductors include other metals, and water. Other conductors include other metals, and water.

3 - Load Load – Part of the circuit that changes the energy of the moving electrons into another form of useful energy. Load – Part of the circuit that changes the energy of the moving electrons into another form of useful energy. Think of a light bulb as a load. Think of a light bulb as a load. As electrons move though the filament of the lamp, the energy of electrons in motion is changed into heat and light energy. As electrons move though the filament of the lamp, the energy of electrons in motion is changed into heat and light energy.

4 - Control Device Control Device – Opens or closes the circuit for electrons to flow. Control Device – Opens or closes the circuit for electrons to flow. A light switch is a great example. The lights are off, electrons can’t flow through to complete the circuit because the switch is open. When the switch is closed, the electrons can flow, and the circuit is closed. A light switch is a great example. The lights are off, electrons can’t flow through to complete the circuit because the switch is open. When the switch is closed, the electrons can flow, and the circuit is closed. Switches can be classified as NO (normally open) or NC (Normally closed) Switches can be classified as NO (normally open) or NC (Normally closed)

Four Values to Measure Electricity Voltage Voltage Amperage Amperage Resistance Resistance Watts Watts

Voltage The force that moves electrons is call VOLTAGE. The force that moves electrons is call VOLTAGE. The unit to measure voltage is known as volts. The unit to measure voltage is known as volts. The common voltage a residential circuit is 120 volts. The common voltage a residential circuit is 120 volts. When calculating formulas, voltage is labeled as “E”. When calculating formulas, voltage is labeled as “E”.

Current Current – Movement of electrons. Current – Movement of electrons. Current is measured in Amperes or amps. Current is measured in Amperes or amps. A typical residential circuit measures 15 Amps. A typical residential circuit measures 15 Amps. The specifications for a common residential circuit are 120V/15A The specifications for a common residential circuit are 120V/15A When calculating formulas, current is labeled as “I”. When calculating formulas, current is labeled as “I”.

Resistance The opposing force in electrical current. The opposing force in electrical current. When electrons flow through a conductor, the are opposed by an insulator. The insulator provides resistance. When electrons flow through a conductor, the are opposed by an insulator. The insulator provides resistance. Coating on a wire is the insulator. Coating on a wire is the insulator. Unit of resistance is the OHM. Unit of resistance is the OHM. OHM’s law states - Voltage / Current = Resistance OHM’s law states - Voltage / Current = Resistance

Ohm’s Law Cont. Voltage (E), Current (I), Resistance (R) Voltage (E), Current (I), Resistance (R) Problem – We need to find the resistance of a 120V/15Amp Circuit. Problem – We need to find the resistance of a 120V/15Amp Circuit. What’s the formula? What’s the formula? E / I = R E / I = R Answer? 8 Ohms Answer? 8 Ohms

Power and Watts Law Power is the time rate of doing work Power is the time rate of doing work Defined in two ways: The rate at which electric energy is delivered to a circuit Defined in two ways: The rate at which electric energy is delivered to a circuit The rate at which an electrical circuit uses electrical energy, or how much work it can do. The rate at which an electrical circuit uses electrical energy, or how much work it can do.

Watts Cont. Most electrical equipment is rated based upon watts used Most electrical equipment is rated based upon watts used For example a light bulb may be rated at 60w, 100w, and so on For example a light bulb may be rated at 60w, 100w, and so on Amount of electricity your dwelling uses is measured in kilowatt/hours used. Amount of electricity your dwelling uses is measured in kilowatt/hours used. Power formula – P = E x I. Power formula – P = E x I. Volts times current equals watts. Volts times current equals watts.

Kilowatt Hours Measures how much electricity your dwelling uses Measures how much electricity your dwelling uses Formula – KWH = Power x Hours /1000 Times rate in $ Formula – KWH = Power x Hours /1000 Times rate in $ Example – 1200w X 2hrs / 1000 (kilo means 1000) x.10$ Example – 1200w X 2hrs / 1000 (kilo means 1000) x.10$ Cost =.24$ Cost =.24$

3 Kinds of Circuits Series Series Parallel Parallel Series – Parallel Series – Parallel

Series Circuits Electrical circuit that only has one path for electrons to flow. Electrical circuit that only has one path for electrons to flow. Open Loop – the circuit is not complete. Open Loop – the circuit is not complete. In simple terms, the switch is open, not allowing electrons to flow to the load to complete the circuit. In simple terms, the switch is open, not allowing electrons to flow to the load to complete the circuit.

Voltage Drop Voltage Drop – if there are two or more loads in the circuit, the volts are distributed among the loads evenly. Voltage Drop – if there are two or more loads in the circuit, the volts are distributed among the loads evenly. The total voltage in each load would equal the source. The total voltage in each load would equal the source. Example – Two lights are wired in the same 120V circuit. The voltage in each load will be 60V. Add the two together, =120V. Example – Two lights are wired in the same 120V circuit. The voltage in each load will be 60V. Add the two together, =120V.

Parallel Circuits The loads are connected between the two conductors that lead to the energy source. The loads are connected between the two conductors that lead to the energy source. There is no voltage drop if two or more loads are connected in parallel. There is no voltage drop if two or more loads are connected in parallel. Example – A vanity light that has three lights. If wired in parallel, the voltage at all three loads is 120V, same as the source. Example – A vanity light that has three lights. If wired in parallel, the voltage at all three loads is 120V, same as the source. If wired in series each light bulb would produce only 40 volts each If wired in series each light bulb would produce only 40 volts each

Series Parallel Loads operate independently. Loads operate independently. Meaning one switch to a light can be turned off, but another can still operate. Meaning one switch to a light can be turned off, but another can still operate. Example of a parallel circuit – In your kitchen, you might have 3 different lights. Each has their own switch. However, they are connected on the same line, at the breaker box. Hence, there are different lines going to each load from the source Example of a parallel circuit – In your kitchen, you might have 3 different lights. Each has their own switch. However, they are connected on the same line, at the breaker box. Hence, there are different lines going to each load from the source

Safety Never work in the circuit while it’s plugged in. Always disconnect the lead from the source. Never work in the circuit while it’s plugged in. Always disconnect the lead from the source. Before powering up the circuit, make sure all wires are properly connected. Before powering up the circuit, make sure all wires are properly connected. Never run the circuit with an exposed wire. Never run the circuit with an exposed wire.

Safety Cont. Never touch an exposed wire while connected. Never touch an exposed wire while connected. Never allow exposed wires touch. It creates a short. Never allow exposed wires touch. It creates a short. If you are unsure if you are allowed to plug in the circuit, ask me. If you are unsure if you are allowed to plug in the circuit, ask me. If an emergency occurs, get my attention immediately. If an emergency occurs, get my attention immediately.