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Electricity Formulas. Current Electricity. Current Electricity- continuous flow of electrons in a circuit Circuit- path for electrons to flow Includes energy source – electrical load- conducting wire. Electric Circuit. Electrical Devices-
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Current Electricity • Current Electricity- continuous flow of electrons in a circuit • Circuit- path for electrons to flow • Includes energy source – electrical load- conducting wire
Electric Circuit • Electrical Devices- • A circuit includes an energy source, a conductor and a load • Switch- • Devices that turns the circuit on or off by closing or opening the circuit • Closed switch- the circuit is complete and electrons to flow • Open switch- the circuit cannot flow through the circuit
Electrochemical Cells • A battery- one simple and convenient source of energy • Electrochemical- package of chemicals that convert chemical energy into electrical energy that is stored in charged particles
Electrochemical • Electrodes- metal stripes that react with the electrolyte • 2 different electrodes such as zinc- copper are used in battery • Electrolyte- liquid or paste that conducts electricity because it contains chemicals that form electrons • Ex. Citrus acid
Wet and Dry Cell • Dry Cell- uses a paste instead of a liquid electrolte • Wet Cell- electrochemical cell that has a liquid electrolyte • Ex. Used in cars and motorized vehicles Terminals- end points in a cell where the battery makes connection
VOLTAGE (V) • Voltage – • Electrical potential between 2 points in a circuit Volt- SI unit for measuring the voltage (V) Voltmeter- device used to measure the voltage of the device
Electric Current • Electric Current- • Measure of the amount of electric charge that passes by a point in an electric circuit each second
Alternating Current • Alternating Current • The flow of current through a plug in the wall • The current flows back and forth at regular cycles • Comes from generators and power lines
Direct Current Direct Current (DC) • Electric current flowing in only one direction • battery
Measuring Current • AMMETER- • Current in a circuit is measured by using this device • The unit of electric current is the ampere (A) • Ampere- • Measure of the amount charge moving past a point in a circuit every second
Conventional current • Conventional current- • Describes current as leaving the source from the positive terminal • Passes through the load and then the meter existing through the negative terminal
Conventional current • When you connect an ammeter or voltmeter to a circuit you need to think in terms of conventional current rather than electron flow • There are 2 terminals on a meter that you use to connect to
RESISTANCE • Resistance- is the degree to which a substance opposes the flow of electric current through it • Conductors- allow the flow of electrons and have very little resistance Measured in ohms Ω Ohmmeter is used to measure ohms
Resistance • When a substance resists the flow of electrons, it slows down the current and converts electrical energy in to other forms • The more resistance it has the more energy it gains from electrons that pass through it • The energy gained by the substance is radiated as heat/ light • Ex. When electrons pass through a floor heater the metal bar will produce heat
Resistance in a circuit • The more resistance it has the smaller the conductivity • Ex. The current will pass through the filament in a light bulb • The filament is the resistor- the material that slows down the current flow • The high resistance to electrons causes the filament to heat up and produce light
Resistors and Potential Difference • In a circuit, electrons have higher potential difference as they enter the resister compared to when they leave • The resister will use up some of the energy • Ex. being at the top of a roller coaster whereby you have a lot of potential energy • At the bottom of the coaster the energy is converted into another form
Types of Resisters • Electronic devices all have resisters • The longer and thinner the wire the higher the resistance
Resistance in a wire • The flow of water in pipes is another model of electricity • Not al pipes transport water equally well • The longer and thinner the pipe the more resistance it has to flow • A pipe with a larger diameter has less resistance – greater flow of water