1. Electric Current Pages 448-451
Chapter 23
Electric Current
Pages

2. Circuits Any path along which electrons can flow is a circuit
Any gaps will prevent flow and stop the circuit
Switch
Break
2 types of circuits
Series
Parallel
Fuse: prevent overloading in circuits. The fuse will only allow a certain amount of current to pass through. If too much passes, it will burn the fuse and break the circuit

3. Series Circuit Current has a single pathway
Total resistance is equal to the sum of the individual resistances
𝑅 𝑇 = 𝑅 1 + 𝑅 2 + 𝑅 3

4. Series Circuit 𝐼=𝑣/ 𝑅 𝑇 Voltage divides among the electrical devices
Ohm’s law applies separately to each device

5. Series Circuit
Main disadvantage:
If one device fails, they all fail

6. Series Circuit 𝑅 1 =3Ω ; 𝑅 2 =2Ω; 𝑅 3 =1Ω;𝑉=6𝑣
𝑅 1 =3Ω ; 𝑅 2 =2Ω; 𝑅 3 =1Ω;𝑉=6𝑣
What is the total resistance?
3+2+1=6Ω
What is the current in the circuit?
𝐼= 𝑉 𝑅 = 6V 6Ω =1𝐴
How much voltage is dropped across each resistor?
voltage divides
2 V

7. Parallel circuit
Each device operates independently of the other devices
Voltage is the same across all devices
Total current divides among the branches. Ohm’s law applies separately to each branch
𝐼 𝑡𝑜𝑡𝑎𝑙 = 𝐼 𝑏𝑟𝑎𝑛𝑐ℎ 1 + 𝐼 𝑏𝑟𝑎𝑛𝑐ℎ 2 + 𝐼 𝑏𝑟𝑎𝑛𝑐ℎ 3 = 𝐼 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑠𝑜𝑢𝑟𝑐𝑒
As the number of branches increases, the overall resistance of the circuit is decreased. The overall resistance of the circuit is less than the resistance of any one of the braches.

8. Parallel circuit 2Ω 2Ω 2Ω 6 v Voltage across each resistor? 6 V
Current in each branch?
I=v/r I= 6/2= 3 A
Current through the battery?
I= sum of all branches= 6 A
Equivalent resistance?
for a pair of resistors, product / sum… 2Ω 2Ω
6 v

9. Assignment
Click on the link to complete the homework