Transcript Document

Electrical Energy- static
and current
electrons
• They carry a negative charge
• Are a small part of an atom
• They are found orbiting around
the nucleus of atom
• When they move from atom to
atom that is electricity
electricity
• Two forms:
• Static: When electrons build up
on the surfaces of objects and
then jump away =(zap!)
• Current: When electrons flow in a
conductor (usually metal)
charge
• Is like a force that affects parts
of atoms
• Things can have a positive
charge, a negative charge, or be
neutral
• Similar charges repel
• Unlike charges attract
• “opposites attract”
Static Electricty
• By rubbing objects together,
electrons can build up on one
object (think balloon activity!)
• The electrons are all alike, so
they try to get away from each
other as best as they can
• Provide them with a way out
and they will take it! (John
Travoltage!)
Positive / negative
charges
• Objects with a negative charge
have an excess of electrons on
their surfaces
• Objects with a positive charge
have less electrons on their
surface
Conduction
• When charges can flow from
one object to another
• They need to touch:
conduction= contact
• Metals (like copper, gold) are
good conductors
Current Electricity
• Series Circuits
• Parallel Circuits
• 1 directional flow • 2 or more
directional flow
• 1 element stops
working the
• Circuit remains
entire circuit
functional even
does not work
without working
elements
http://www.andamooka.org/reader.pl?pgid=liecDCDC_5
Energy Flow Cont’d
• Electrons (negative charges)
flow in the opposite direction –
from the negative terminal
• If a circuit is not a complete
loop it will not work as intended
• No electrical connection is
made and the current stops
• An incomplete loop is called an
open circuit
• Electricity only flows through a
closed circuit!
Energy Flow
• Energy that flows through a circuit is
called a current or amperage,
measured in amps
• “Pressure” of that energy flow is
called voltage, measured in volts
• When hooked up to a battery the
current flows out of the negative (-)
end and around through the circuit
back into the positive (+) end
More Energy Flow
• Resistance occurs when
something extra is introduced
into the circuit (i.e. light bulb).
This is called a Load.
• More light bulbs = more
resistance
• More resistance = less current =
dimmer light produced
AC or DC?
• Alternating
current
• Ex. power plant
• Direction of the
current reverses;
can easily
change the
voltage (with
transformers)
• Direct current
• Ex. batteries, fuel
cells, solar cells
• Current flows in
one direction
from negative
terminal to
positive terminal
Electricity Basics
• 3 basic units in electricity
• Voltage (V), measured in volts
• Current (I), measured in amps
• Resistance (r), measured in ohms
Ohm’s Law:
I=V/r
Increasing voltage will make more
current flow
Decreasing resistance will also make
more current flow