1. Current electricity

2. Learning goals We are learning the difference between:
potential difference
current
resistance.

3. Potential difference

4. Potential difference potential energy: the energy stored in an object
each electron has potential energy

5. Potential difference
battery: chemical potential energy in the electrolyte in its electrochemical cells
chemicals in electrolyte react with electrodes
causes difference in amount of electrons between 2 terminals
one terminal mainly negative charges
other terminal mainly positive charges
negative charges = electrons, so can move
attracted to positive charges at positive terminal

6. Potential difference
conductor (copper wire) connected to both terminals
electrons flow from negative to positive terminal
difference in electrical potential energy between two points in a circuit is called the potential difference or voltage (V)
this difference causes current to flow in a closed circuit
the higher the potential difference in a circuit, the greater the potential energy of each electron

7. Measuring potential difference
measured with a voltmeter
unit is the volt (V)

8. current

9. Electric current
a measure of the amount of electric charge that passes by a point in an electrical circuit each second
as long as battery continues to separate charges on its terminals, electrons continue to flow
waterfall

10. Measuring current measured using an ammeter
unit of electric current is the ampere (A)
1A = electrons are flowing every second

11. Electric Current at Home
Houses have safeguards installed in case too much current is being used.
Fuses (older homes) vs Circuit breakers (newer homes)
Circuit breakers are switches which turn off if too much current exists.
Most homes have a total of A of electricity entering from their providers.

12. The Human Body
The human body has it’s own electrical signals that exist naturally.
Even small electrical shocks to the system are dangerous:
0.001A: Small tingling sensation
A: Can cause muscles to contract
1-4.3A: Can stop your heart if passed through chest.
An outlet that powers a computer can deliver 15A of current.

13. resistance

14. resistance
the degree to which a substance opposes the flow of electric current though it
measured in ohms (Ω)
measured using an ohmmeter

15. resistors any material that can slow current flow
used to control current or potential difference in a circuit
converts potential energy to another form of energy

16. examples

17. 4 Factors that Affect Resistance
Type of Material: Insulator vs. conductor.
Cross-sectional area: The larger the diameter, the less resistance.
Length: The shorter the length, the less resistance.
Temperature: The colder the wire, the less resistance.

18. Learning goals We are learning the difference between:
potential difference
current
resistance.

19. Please complete What is another name for stored energy?
How is an apple falling from a tree like the potential difference in a battery?
What does potential difference measure?
What is another name for potential difference?
What is electric current?
What does resistance refer to in terms of electron flow?

20. Please Complete
P557 #1,4
P561 #2
P566 #2,3,5,6,7