Upload
all-saints-science
View
6.191
Download
0
Tags:
Embed Size (px)
Citation preview
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