E N D
1. Aim: How can we explain electric current and resistance?
2. Electron Flow Current flows from negative to positive
3. Electric Current The “flow of charge” – the amount of charge that passes a single point in a period of time
5. A current of 2.0 A is flowing in a circuit. How much charge passes a given point in the circuit in 30 seconds?
I = ?q
t
2.0 A = ?q
30 s
(2.0 A)(30 s) = ?q
60 C = ?q
7. Resistance A measure of how easy or difficult it is for current to flow
8. Ohm’s Law
13. Graph of V vs. I
14. Resistance Increases when: Length of conductor increases/decreases
Cross sectional area of conductor increases/decreases
Temperature of metal conductor increases
Temperature of non-metal conductor decreases
15. Resistance of Conducting Wire R = Resistance (O)
? = Resistivity (O•m)
L = Length (m)
A = Cross Sectional Area (m2)
16. Resistivity
17. Calculate the resistance of a 2.0-m long Aluminum wire with a cross sectional area of 1.5 x 10-3 m2.
R = ?L
A
R = (2.82 x 10-8 O•m)(2.0 m)
(1.5 x 10-3 m2)
R = 3.8 x 10-5 O