Transcript electric current

1-3
Electric Current and Magnetic Fields
Electric Current
• Electric Charge - all protons and
electrons have an electric charge.
• The flow of electric charges produce
an electric current.
• Ampere (A or amps) - unit used to
measure the amount of charge that
flows in a given time
• An electric current produces a
magnetic field (p. 31)
• The field produced effects compasses
just as a magnet does
Moving Charge and Magnetism
• All magnetism is caused by the
movement of charges.
• The movement of charges is also
responsible for electric current.
Electric Circuits
• Electric currents need a circuit in
order to flow .
• A circuit is a closed path for the
current to travel through.
• All electrical devices contain circuits
• All circuits have the same basic features
• A source of electrical energy (power source)
• Ex. Battery
• A device that is run by electrical energy
• Ex. Light Bulb
• Conducting wires and a switch
• See p. 31
Conductors and Insulators
• Electric current does not flow through every
material
• Conductors allow electricity to flow freely
• Ex. Copper, silver, iron, aluminum
• Conductors have loosely bound electrons in
their atoms, that allows the electrons to to
flow through the material-->forms a current
• Insulators do not allow electricity to flow
freely
• Ex. Rubber, wood, glass, plastic
• Electrons are bound tightly to their atoms
and do not flow easily.
• Conducting copper wire is covered by a
plastic coating so that it can be handled
safely while currents flow through it.
Electrical Resistance
• A resistor uses electrical energy as it
interferes with the flow of charge
• Many times the energy is transferred into
another form
• Ex. Light bulb --> electrical energy to light and heat
energy
• Best example:
Walking through a crowd. Stand up,
let’s try it.
Superconductors
• A material that has NO electrical
resistance
• This would allow an electrical current to
flow with out losing any energy
• Computers could be the size of a watch
and be just as effective and powerful as a
typical desktop computer.