Electrical Energy- static and current

electrons

• Are a small part of an atom

• They are found orbiting around the nucleus of atom

• They carry a negative charge

• 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• 1 directional flow• 1 element stops

working the entire circuit does not work

• Parallel Circuits• 2 or more

directional flow• Circuit remains

functional even 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

I = V / r

Increasing voltage will make more current flow

Decreasing resistance will also make more current flow