1. Electricity

2. What is electricity?
Electricity is the flow of electric current through a conductor.
In mechanics the basic property of matter is mass, in electricity the basic property is charge.

3. How does electricity get to your home?

4. Where do charges come from?
There are two kinds of charges: positive and negative.
Protons have a positive charge.
Electrons have a negative charge.

5. Where do we find charges?
Charged particle are found in the atom.
Protons are found tightly bound in the nucleus.
Electrons are found whirling around the nucleus in orbits.

6. How do charges behave?
Charges can never be created or destroyed (Conservation of charge).
Unlike charges attract, like charges repel.

7. By what law do charges behave?
Charges behave according to Coulomb’s Law. This states that the force can be attractive or repulsive and weakens with distance.

8. What makes charges move?
Charges can be made to move when they are placed in a changing magnetic field.
A moving magnet or a moving coil of wire near a magnet induces an electric current.

9. How is an electric current measured?
An electric current is measured in Amps.
An amp is the flow of 1 Coulomb of charge per second.
A coulomb is 6.24 x 1024 electrons

10. What other properties does electricity have?
Electricity has a voltage which is like electrical pressure. This is measured in volts.
It also encounters electrical resistance (friction) which is measured in ohms.

11. What law relates these quantities?
Ohm’s law relates the quantities of electric current. It states : I=V/R
R=resistance (Ohms)
I=Current (Amps)
V=Voltage (Volts)

12. Is there an analogy to explain Electric current ?

13. What affects resistance?
Materials that offer a large Electrical resistance are called good insulators.
Materials that offer little resistance are called good conductors.

14. Are there other factors?
Distance also affects resistance. The longer the distance the greater the resistance.
Thick wires also have less resistance than thin wires.

15. What is electric power?
Electric power is the amount of energy available per time
It is measured in watts or kilowatts
The equation is P=VI