ElectricityElectricity

Static, Currents, CircuitsStatic, Currents, Circuits

Electrical FieldsElectrical Fields Is a force field that surrounds an electric Is a force field that surrounds an electric

charge or group of chargescharge or group of chargesSimilar to force field that surrounds a mass Similar to force field that surrounds a mass

– gravitational field– gravitational field

Electrical FieldsElectrical FieldsElectric field has magnitude and directionElectric field has magnitude and directionVector quantity represented with electric Vector quantity represented with electric

field lines (out from positive, in to negative)field lines (out from positive, in to negative)

Electricity that Electricity that movesmoves……

CurrentCurrent: The flow of electrons : The flow of electrons from one place to another.from one place to another.

Measured in Measured in amperesamperes (amps) (amps)KineticKinetic energy energy

There are 2 types of currents:There are 2 types of currents:

Direct Current (DC)Direct Current (DC) – Where – Where electrons flow in the electrons flow in the samesame direction in a wire. direction in a wire.

There are 2 types of currents:There are 2 types of currents:

Alternating Current (AC)Alternating Current (AC) – – electrons flow in electrons flow in differentdifferent directions in a wiredirections in a wire

AC vs. DCAC vs. DC

AC/DC: What's the Difference?

What is Resistance?What is Resistance?

The The oppositionopposition to the flow of an to the flow of an electric current, producing electric current, producing heatheat..

The The greatergreater the resistance, the the resistance, the lessless current gets through. current gets through.

GoodGood conductors have conductors have lowlow resistance.resistance.

Measured in Measured in ohms.ohms.

What Influences Resistance?What Influences Resistance?

Material of wireMaterial of wire – aluminum and – aluminum and copper have low resistancecopper have low resistance

ThicknessThickness – the thicker the wire the – the thicker the wire the lower the resistancelower the resistance

LengthLength – shorter wire has lower – shorter wire has lower resistanceresistance

TemperatureTemperature – lower temperature has – lower temperature has lower resistancelower resistance

Electrical Potential Electrical Potential EnergyEnergy

Energy a charge has due to Energy a charge has due to its location in an electric its location in an electric fieldfield

Just as GPE is the work Just as GPE is the work required to lift object, EPE is required to lift object, EPE is work done to push charge work done to push charge against the electric field of against the electric field of something else that is something else that is charged.charged.

What is Voltage?What is Voltage?

The The measure of energymeasure of energy given to given to the charge flowing in a circuit.the charge flowing in a circuit.

The The greatergreater the voltage, the the voltage, the greater the force or “pressure”greater the force or “pressure” that drives the charge through the that drives the charge through the circuit.circuit.

Difference b/t Volts and AmpsDifference b/t Volts and Amps

Example – you could say that…Example – you could say that…AmpsAmps measure measure how muchhow much water water

comes out of a hose.comes out of a hose.VoltsVolts measure measure how hardhow hard the water the water

comes out of a hose.comes out of a hose.

Ohm’s LawOhm’s Law

Resistance = Voltage / CurrentResistance = Voltage / Current

Ohms = Volts / AmpsOhms = Volts / Amps

Practice with Ohm’s LawPractice with Ohm’s Law

OhmsOhms VoltsVolts AmpsAmps

44 100100 2525

1515 150150 1010

22 3030 1515

99 4545 55

66 4848 88

CircuitsCircuitsComplete path for electrons to flow Complete path for electrons to flow

(circuit)(circuit)

Battery and Light bulbBattery and Light bulbElectrons flow from negative terminal to Electrons flow from negative terminal to

positive terminalpositive terminal

How can we How can we controlcontrol currents? currents?

With With circuitscircuits..CircuitCircuit: is a : is a pathpath for the flow of for the flow of

electrons. We use electrons. We use wireswires..

There are 2 types of circuits:There are 2 types of circuits:

Series CircuitSeries Circuit: the components : the components are lined up along are lined up along oneone path. If path. If the circuit is broken, the circuit is broken, all all components turn off.components turn off.

Series CircuitSeries Circuit

There are 2 types of circuits:There are 2 types of circuits:

Parallel CircuitParallel Circuit – there are – there are severalseveral branching paths to the branching paths to the components. If the circuit is components. If the circuit is broken at any one branch, broken at any one branch, only only the components on that branch the components on that branch will turn offwill turn off..

Parallel CircuitParallel Circuit

Parallel CircuitParallel CircuitSeries CircuitSeries Circuit

Schematics of Schematics of CircuitsCircuits

Equivalent Equivalent ResistanceResistance

Equivalent Equivalent ResistanceResistance

Conductors vs. InsulatorsConductors vs. Insulators

ConductorsConductors – material through – material through which electric current flows which electric current flows easilyeasily..

InsulatorsInsulators – materials through – materials through which electric current which electric current cannot cannot movemove..

ExamplesExamples

ConductorsConductors::MetalMetalWaterWater

InsulatorsInsulators::StyrofoamStyrofoamRubberRubberPlasticPlasticPaperPaper