1. Probe the fundamental principles and applications of electricity

2. Electric Charge Charge Force Fields
Atoms lose electrons and now have a positive charge
Shortage of electrons causes an electric charge
Force
Like charges repel
Opposite charges attract
Fields
Area around an electric charge that effects others
Depends on amount of charge and distance

3. Static Electricity and Charging
Charges between stationary objects
Charging by friction
Sliding an object across something to pick up a charge
Rubbing a balloon on hair, socks on carpet
Charging by contact
Pick up a charge by touching something that has a charge
Charging by Induction
No contact needed to change charge of objects

4. Static Discharge
Law of conservation of charge-total charge is constant
Discharge occurs when charges can change suddenly
Examples
Lightning-cloud is negative, ground is positive
Shock from doorknob-finger is negative, doorknob is positive

5. Current Electric current Alternating Current Direct Current
Continuous flow of electric charge
Unit is ampere, A
Current flows in opposite direction of charge flow
Alternating Current
Charge regularly reverses direction
What comes out of a socket
Direct Current
Charge flows in one direction
Batteries

6. Conductors & Insulators
Electrical conductor
Charge flows easily
Metal, copper, silver
Sea of electrons in metals
Electrical insulator
Does not flow easily
Wood, plastic, rubber, air

7. Resistance Resistance Superconductor
Inability of electrons to flow easily
Thickness, length, and temperature affect resistance
Thick wire-less resistance
Long wire-high resistance
High temperature-high resistance
Measured in Ohms, W
Superconductor
Super cooled object that has no resistance
Cooled to below 138K

8. Voltage & Ohm’s Law Potential difference Sources Ohm’s Law
Difference in electrical potential energy between two places
Measured in volts, V
Call it voltage
Sources
Batteries, convert chemical to electrical energy
Solar cells convert solar to electrical energy
Generators convert mechanical to electrical energy
Ohm’s Law
Increasing voltage increases current
Increasing resistance decreases current
Voltage is the product of current and resistance
V=I x R

9. Circuits Circuit diagram Series Parallel
Shows the flow of current, resistors, sources, and devices in a circuit
Open circuit-charge cannot flow completely “Off”
Closed circuit-charge can flow completely “On”
Series
Charge has only one path to move
If one element stops, all stops
Current the same through each element
Voltage different through each element
Christmas lights
Parallel
Two or more paths
If one element stops, others can still work
Current different through each element
Voltage the same through each element
Houses on parallel circuits

10. Power and Energy Power Energy
Rate at which electrical energy is converted
Measured in Watts
P=I x V
Energy
Amount of power used over time
Measured in kilowatt Hours, kWh
E=P x t

11. Safety Fuse Circuit breaker Personal safety
Prevents overloading of a circuit
Metal melts causing an open circuit
“blowing a fuse”
Circuit breaker
Switch that opens when current is too high
Must be reset
Personal safety
Insulation on wires
Grounding-excess charge transfers to the earth
Ground-fault circuit interrupter-opens the circuit if the currents are not equal