Electricity & Magnetism Unit 6
Recall that Atoms l Have neutrons, protons, and electrons. l Protons are positively charged l Electrons are negatively charged l Opposite charges attract l Same charges repel
Electrons l Are located on the outer edges of atoms they can be moved. l A concentration of electrons in an atom creates a net negative charge. l If electrons are stripped away, the atom becomes positively charged.
The world is filled with electrical charges: + + - + - - + + + - + + - - - + - + - -
l Balloon phet Balloon Demo
Potential electrical energy is l Static Electricity called: - - - - - + + - + - + +
Static Electricity l The build up of an electric charge on the surface of an object. l The charge builds up but does not flow. l Static electricity is potential energy. It does not move. It is stored.
3 Ways for Static Electrcity to Build Up l Friction - rubbing l Conduction direct contact l Induction through an electrical field (not direct contact) l phet Balloon Demo
Static Discharge l Occurs when the potential energy of static electricity moves and evens out the charges/balances the charges again
PHET John Travoltage l link to Demo
Moving/Kinetic Electrical Energy is Current Electricity l Current: The flow of electrons from one place to another. l Flows through wires l Measured in amperes (amps)
How can we control currents? l With circuits. l Circuit: is a path for the flow of electrons. We use wires.
There are 2 types of currents: l Direct Current (DC) Where electrons flow in the same direction in a wire. l Batteries are DC l (chemical energy)
There are 2 types of currents: l Alternating Current (AC) electrons flow in different directions in a wire l Due to changing poles of a magnet spinning by wire l Negative poles cause the negative electrons to be repelled l Wall outlets are AC l https://phet.colorado.edu/en/simulation/ generator
There are 2 types of circuits that DC and AC electricity can use: l Circuit = the path the electricty flows l Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.
Series Circuit
There are 2 types of circuits: l Parallel Circuit there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.
Parallel Circuit
Materials can be either conductors or insulators l Conductors material through which electric current flows easily. l Insulators materials through which electric current cannot move.
Examples l Conductors: l Metal l Water l Insulators: l Styrofoam l Rubber l Plastic l Paper
What is Resistance? l Electrical friction l The opposition to the flow of an electric current, producing heat. l Measured in ohms. l Abbreviated as R l Good conductors have low resistance.
What is Voltage? l The measure of the force of energy given to the charge flowing in a circuit. l The greater the voltage, the greater the force or pressure that drives the charge through the circuit. l Measured in volts l Abbreviated as V
What is Current? l The rate that the electricity flows l Measured in amperes (Amps) l Abbreviated as I
Ohm s Law the relationship between voltage, resistance and current Voltage (V)= current(i) X resistance(r ) l the force = the flow of electricity X the resistance l V = I x R
How is electricity produced? l Generator a machine that changes mechanical energy to electrical energy phet link l Usually use moving magnets to create currents in coils of wire. l Electrical energy video
How electricity creates light l Thin wire in the bulb creates lots of resistance ( friction) = heat l Heat energy converts to light energy l How light bulb works
Related Activities l phet lab on Ohm s Laws l Ohm s Laws Calculation Worksheet l Electricity video and worksheet l Build series and parallel Circuits