ELECTRICITY: Creating Current

Electricity Generator OUTCOME QUESTION(S): S1-3-08: What is “electricity” and how is it created? Vocabulary & Concepts  Electricity Generator

(Current) Electricity: Creating “Electricity” Different sources exist for creating energy from free electrons and generating an electric current Batteries Solar Panels Hydro Dams … What other ways have you seen to create electricity? (Current) Electricity: the flow of electrons around a circuit.

Essentially just converting one form of energy into another form Most electricity is creating using two basic steps: Remove electrons from one location (takes energy) Let electrons flow back (releases energy) Essentially just converting one form of energy into another form

More detail to come on batteries…. 1. Chemical: source converts chemical energy into electrical energy. Reaction separates electrons from metal (+) Energized electrons collect at other metal (-) Electrons flow back to (+) metal More detail to come on batteries….

2. Thermoelectric: source converts heat energy into electrical energy. Metals heated at one end and cooled at other Energized electrons flow towards cool side Called a thermocouple / thermopile Thermocouples are used as safety control devices in furnaces, engines and appliances

3. Photoelectric: source converts solar energy into electrical energy. Light energy separates electrons from material Energized electrons accumulate on “collector” Creates a weak flow of electrons Remember: visible light is just one form of wave around us - Some are low energy (radio wave) some high energy (x-ray)

Piezo comes from the Greek word meaning pressure 4. Piezoelectric: source converts mechanical energy into electrical energy. (some) Materials polarize when squeezed various crystals, ceramics, bone Creates charge separation across the faces Electrons flow when faces are connected Piezo comes from the Greek word meaning pressure

The piezoelectric effect also works in reverse: Applying current to a crystal causes it to change shape (vibrate) Ultrasound machines, sonar, microphones, watches/clocks, push lighters, all use the piezoelectric effect

Device is called a generator 5. Electromagnetic: source converts mechanical energy into electrical energy. Coil of wire spinning through a magnet creates a flow of energized electrons Device is called a generator An energy source is needed to turn generator – wood, coal, falling water, nuclear reaction…

97.6% of Manitoba energy comes from dammed water turning the generator to create the electricity

STATIC Vs. CURRENT ELECTRICITY SIMILAR DIFFERENT Both: need input of energy to create charge (friction or other source) Static: displaced electrons are localized Current: displaced electrons move Both: 1st step is charge separation 2nd step is charge transfer (neutral object or battery) Static: brief transfer of small amounts of charge Current: continued transfer of large amounts of charge Both: will discharge (run out) when all electric charge is transferred back Static: discharges randomly Current: discharges through a conducting path

CAN YOU ANSWER THESE QUESTIONS? S1-3-011: What is “electricity” and how is it created? Vocabulary & Concepts  Electricity Generator

CURRENT ELECTRICITY: Components

Volt Voltmeter Current Ampere Ammeter Resistance Resistor Ohm Load OUTCOME QUESTION(S): S1-3-09/10/12: What do current, voltage and resistance mean for electrons? Vocabulary & Concepts  Cell Coulomb Voltage Volt Voltmeter Current Ampere Ammeter Resistance Resistor Ohm Load

metal to lose electrons – (-) electrode (anode) Cell: device that uses a chemical reaction to create a flow of electrons between different materials. NEED: metal to lose electrons – (-) electrode (anode) metal to gain electrons – (+) electrode (cathode) chemically reacting substance – electrolyte The acidic lemon juice acts as the electrolyte to aid the chemical reaction

Rod: (+) electrode (cathode) The original Voltaic “wet” cell does not have practical use today and has been replaced by the “dry” cell - battery Rod: (+) electrode (cathode) Casing: (-) electrode (anode) electrolyte paste

Electrons are measured and counted in bundles called a coulomb: Cell Measurements: Electrons are measured and counted in bundles called a coulomb: 1 coulomb = 6.25 quintillion (6.25 x 1018) electrons Think of a coulomb as very, very large “dozen” 1. Voltage (V) Electrical potential of electrons in a source: electrons convert their potential energy into work Potential: unrealized ability to accomplish something Voltage: energy the electrons have to potentially do something

Measured by a Voltmeter Units: Volt (V) = Q E E is energy/work potential in joules Q is the number of coulombs Voltage (volts) measures the potential energy available in every coulomb of electrons As electrons move to the other end of the source they lose all potential (stored) energy

1.5 joules of energy released by every coulomb of electrons 1.5 Volt battery 1.5 joules of energy released by every coulomb of electrons 0 Volts (+) electrode (-) electrode electrolyte paste 1.5 Volts 550 V – typical Power station 120 V – typical wall outlet 1.5 V – typical battery

2. Current (I) The rate (speed) at which electrons move through the conductor. Measured by an Ammeter Units: Ampere /Amps (A) I = t Q Q is the number of coulombs t is time in seconds Current (amps) measures the number of electrons passing a point every second

1 Amp = electrons moving at a rate of 1 coulomb per second 0.83 A – current needed for a typical light bulb 0.2 A – severe burns, heart stops, lungs stop (“let go” threshold) 0.02 A – breathing affected, muscles contract 0.002 A – muscles tingle (good shock) Its not the voltage that kills, it’s the current: the number of electrons running through you

Energy taken is converted as work or lost as heat 3. Resistance (R) Anything that slows down electrons and takes potential energy away in the process. Resistors are electrical components used to control the current and voltage to protect the device. Units: ohm (Ω) The loss of potential energy as electrons slow through a resistor is called the “voltage drop” Energy taken is converted as work or lost as heat

e- Load + - e- a resistor that converts energy for use Resistor ● + - Load a resistor that converts energy for use Resistor slows electrons and take energy as heat e- Even the conducting wire provides some resistance – takes some energy away converting it to heat

CAN YOU ANSWER THESE QUESTIONS? S1-3-09/10/12: What do current, voltage and resistance mean for electrons? Vocabulary & Concepts  Cell Coulomb Voltage Volt Voltmeter Current Ampere Ammeter Resistance Resistor Ohm Load