1. Resistance

2. Resistance is the property of a substance that measures its ability to impede the flow of electrons in conductors.
As electrical current flows through a resistor,electric potential (voltage) is lost. (I.e. the electrons have more potential energy before passing through the resistor)

3. Symbol: R
Unit: ohm (Ω)
Measuring Device: Ohmmeter
What does a resistor do when it is in a circuit?
Reduces the current in a circuit

4. Ohm’s Law – the potential difference between 2 points on a conductor is proportional to the electric current flowing through the conductor
Ohm’s Law: V = I x R
I R V

5. Name
Symbol in Formula
Symbol for Unit
Current I A
Voltage/Potential Difference V
Energy E J
Charge Q C
Resistance R Ω

6. Ohm’s Law:
The potential difference between two points on a conductor is proportional (directly related) to the electric current flowing through the conductor.

7. Sample Calculations
A load has 1.2 A of current flowing through it. The voltage across the load is 6.0 V. Calculate the resistance of the load.
Given: I = 1.2A
V = 6.0V
Required: R = V÷I
Analysis: R = 6.0÷1.2
Solution: R = 5.0 Ω (this is option z on your computer)

8. 2. Calculate the Resistance given the following data:
V = 120 V
I = 1.1 A
b) V = 1.5 V
I = A