Electricity and Electrical Circuits

Chapter SectionsO 1 - Electrical Circuits

O 2 - Current and Voltage

O 3 - Resistance and Ohm’s Law

1 - Electrical Circuits

Electrical CurrentO The flow of electricity through wires,

motors, light bulbs, and other devices

O Typically the flow of electrons

O Very dangerous – your nerves use electricity to function

Electrical CircuitsO A complete path through which

electricity travels

O Wires in circuits are like pipes that carry water

Electrical SymbolsO Circuit diagrams use

symbols to make drawing circuits simpler and easier

Open and Closed Circuits

O Open circuit has a break which stops the flow of electricity

O Closed circuit has no breaks

O Switches and Circuit Breakers open and close a circuit

2 - Current and Voltage

CurrentO Current is measured in

amperes (A)

O Current flows from positive to negative

O Current is the flow or motion of charges

Measuring currentO Measured with an

ammeter

O The current must pass through the meter

O Can be either AC or DC, which we will learn about in Chapter 14

VoltageO Measured in volts (V)

O Measures electrical potential energy

O A higher potential difference (more volts) means that more work can be done

Measuring VoltageO Measured with a volt meter

O A multimeter can measure voltage, current, and resistance

BatteriesO Use chemical energy

to create voltage.

3 - Resistance and Ohm’s Law

ResistanceO The measure of how

strongly a wire or other object resists current flowing through it

Measuring ResistanceO Measured in ohms (Ω = omega)

Ohm’s Law

Using Ohm’s Law

Conductors and Insulators

O Electricity flows easily through conductors

O Electricity is blocked by insulators

O Materials in between these two are called semiconductors

PotentiometersO A potentiometer is a

variable resistor that is used to control the flow of current

O Dimmer switches and volume controls are examples