1. Warm Up #13
What is an electric current?

2. Lesson 2: Electric Current and Simple Circuits
Ch. 9 Electricity
Lesson 2: Electric Current and Simple Circuits

3. Essential Questions
What is the relationship between electric charge and electric current?
What are voltage, current, and resistance? How do they affect each other?

4. What is the path to turn on a light? activity
Using the following objects how could we light the lightbulb?
Let’s test it……
What happened and why did it happen?

5. Electric current and electric circuits
Electric current – the movement of electrically charged particles
Electric circuit – a closed, or complete, path in which an electric current travels
Electric currents flow in a closed path to and from a source of electric energy

6. What is electric resistance?
Electric resistance – a measure of how difficult it is for an electric current to flow in a material
Measured in Ohms (Ω)
Good conductors have a low electric resistance
Good insulators have a high electric resistance
Material’s electric resistance depends on material’s length and thickness
Thick material has less resistance than thin material
Increasing the length also increases its electric resistance

7. What is voltage?
Voltage – the amount of energy the source uses to move one coulomb of electrons through the circuit
High voltage = more electric energy
Low voltage = less electric energy

8. Warm up #14
What do you think Ohm’s Law is?

9. Ohm’s Law
Ohm’s law – a mathematical equation that describes the relationships among voltage, current, and resistance
As the voltage of a circuit’s electric energy source increases, the current in the circuit increases too
As the resistance of a circuit increases, the current decreases

10. Ohm’s Law

11. Ohm’s Law
The current through a lightbulb is 0.5A. The resistance of the lightbulb is 220Ω. What is the voltage across the lightbulb?