1. Electrical Resistance
Let’s start on page 63 of this book 
We will have eight (8) talking points today!

2. 1. Definition, (words)
The electrical resistance of an electrical element measures its opposition to the passage of an electrical current.
Electrical resistance shares some conceptual parallels with the mechanical notion of friction.
The SI unit of electrical resistance is the ohm (Ω).

3. 2. Definition, (mathematically)
The resistance of an object is defined as the ratio of voltage across it to current through it.
Resistance = Voltage / Current

4. Georg Simon Ohm
German physicist
3. OHM’s LAW
The relationship between resistance, voltage, and current is known as OHM’s LAW!

5. 4. Circuits and Resistance
In a SERIES circuit current is CONSTANT and voltage CHANGES.

6. 4. Circuits and Resistance
In a PARALLEL circuit current CHANGES and voltage is CONSTANT.

7. Look at page 68 (top) for series rules and page 69 (side) for parallel rules!

8. 5. Classify electrical properties (page 70-71)
Conductors –
Insulators –
Semi-Conductors –

9. R = r l / A = ___________ l = ___________ A = ___________
6. Equation and Factors that Influence Electrical Resistance (page 66 –bottom)
R = r l / A
= ___________
l = ___________
A = ___________

10. 7. Resistivity is inverse to Conductivity

11. 8. Calculating TOTAL resistance, current, and voltage in series and parallel circuits.

12. Page 74: 11, 12, 13, 15-20
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