Ch. 2Sec. 2

Electric Current

electric current

• continuous flow of electric charges thru. a material

• unit=amp

Representing an Electric Current

electric circuit

• complete, unbroken path thru. which electric charges can flow

Simple Circuits activity

electrical potential• potential energy per unit of electrical charge

2 factors that affect flow of current

voltage (potential difference)

resistance

conductor

•material through which a charge can flow easily

conductor

• material thru which electric currents move freely

• electrons are only loosely bound to their atoms

• eg. copper, silver

conductors

• silver • copper • gold • aluminum • iron

• steel • brass • bronze • mercury • graphite • water

insulator

•material through which a charge can not flow easily

insulator=

• charges are not able to move freely

• electrons are bound tightly to their atoms

• eg. plastic, wood

insulators

• glass • rubber • plastic• asphalt • fiberglass • porcelain • ceramic

• quartz • (dry) cotton • (dry) paper • (dry) wood • air • diamond

Conductors and Insulators [00:59]

Conductors and Insulators Online Activity

Voltage (potential difference)

1.1. DifferenceDifference in electrical potential between 2 places

2. Causes current to flow thru. electric circuit

3. unit = volt

Voltage in a circuit is similar to the difference in potential energy on a roller coaster.

POTENTIAL DIFFERENCE

Just as water flows downhill, electrons flow from places of higher potential to places of lower potential. The difference in electrical potential between two places is called potential difference.

WHAT IS VOLTAGE?Voltage is potential difference measured

by a ______________ ?

VOLTMETERThe unit of measure in potential difference is called the volt. For that reason, potential difference may be called voltage.

ELECTRON FLOWElectrons will flow as long as there is a potential difference or voltage between two parts of a circuit.

WHAT CAUSES CURRENT TO FLOW?

Voltage causes current to flow through anelectric circuit. The flow of electrons through amaterial is called ___________?

Electric Current

voltage source• creates potential difference

• eg. battery & generator

• increase in voltage causes greater flow of electric current

voltage source

•has 2 terminals

resistance• measure of how difficult it is for

charges to flow thru. a material• unit = ohm

factors that

determineresistance

of a wire

material from

which wire is

made

length of

wire

diameterof

wire

temp. of

wire

Charges flow through the wire, not the

bird, because the wire offers

less resistance.

BBC - Schools Science Clips - Circuits and

conductors

BBC- Schools Science Clips-Changing Circuits

http://www.learningcircuits.co.uk/

What happens when an electric current is produced?

• a continuous flow of charges travel through a material

Contrast electric current and static electricity.

• An electric current is a continuous flow of charge. In static electricity, charges build up but do not flow.

Explain why electric current cannot exist if an electric

circuit is broken.• charges cannot flow because the path is not complete

Define conductor and insulator.

• conductor = material is a material through which charges can flow through easily

• insulator = material through which charges cannot flow through easily

List materials that make good conductors. List materials

that make good conductors.

• good conductors = silver, copper, aluminum and iron

• good insulators = rubber, sand, plastic and wood.

Create a concept map using the following terms:

• Electric current

• Electric circuit

• Conductor

• Insulator

• Voltage

• Resistance

• Ohms

• Amperes

• Volts

Electriccurrent

resistance voltage

ohms volts

amps