1. Notes 6 - Electricity

2. What is electricity?
Electricity - the movement of electrons in a material toward an area of positive (+) charges.
Since electrons are negative, they are attracted to positive charge and repelled by negative charge

3. Potential Difference (voltage)
Why aren’t birds on power lines electrocuted?
Because there is no potential difference between its feet.

4. What is voltage?
Voltage – the potential energy difference that makes charged particles move
Without voltage, electricity will not flow
Just like a falling ball, a charged particle moves from high potential energy to low potential energy
The greater the difference between the high and the low, the greater the voltage

5. Batteries are voltage sources
Every electric device needs a voltage source in order to work
9 volt battery has two terminals: a negative (-) and a positive (+) with a 9V potential difference between them
The negative terminal is the high
The positive terminal is the low

6. How does a battery work?
A common battery is filled with a pasty mixture
When in use a chemical reaction within the paste strips electrons from a carbon rod.
These electrons collect on the zinc exterior of the battery forming the negative terminal

7. What is current?
Current – the rate at which electric charges move through a conductor
Just like a ball rolling down hill, the electric charges will move faster if they move down a bigger hill.
The greater the voltage the faster the current will flow
current flows from the negative terminal of a battery to the positive terminal

8. What is resistance?
Resistance – The friction that slows down moving charged particles
As charged particles move through a material they bump into other particles – this creates friction or resistance
The more resistance the less current
This friction produces heat
The filament of a light bulb gets so hot it glows

9. Electrical Conductors
electrical conductors allow charged particles to flow easily
They have low resistance
Metals like copper, zinc and gold, make the best electrical conductors

10. Electrical Insulators
electrical insulators do not allow electrons to move
they have a high resistance
Plastic, wood, rubber and glass are all insulators

11. Use of Conductors & Insulators
Free electrons in the copper allow the electric charge to flow through the wire.
Insulators:
The structure of the rubber does not allow the flow of electrons.
( electrons remain in place )

12. Ohm’s Law the amount of resistance must be calculated using Ohm’s Law
Ohm’s Law states that:
resistance = voltage/current
R = V / I
Why the I and not C? C was already used for something else

13. Electricity Term
Description
Unit of measure
Formula
Voltage
Current
Resistance

14. Electricity Term
Description
Unit of measure
Formula
Voltage
Pushes current forward
Volts (V)
V = IR
Current
Resistance

15. Electricity Term
Description
Unit of measure
Formula
Voltage
Pushes current forward
Volts (V)
V = IR
Current
The rate at which charged particles move
Amps (A)
I = V R
Resistance

16. Electricity Term
Description
Unit of measure
Formula
Voltage
Pushes current forward
Volts (V)
V = IR
Current
The rate at which charged particles move
Amps (A)
I = V R
Resistance
Holds current back
Ohms ()
R = V I