1. Circuits

2. Series Circuits Big R = Big DV small R = small DV
Current is the same everywhere
Voltage gets divided up based on the resistance

3. Parallel Circuits Current gets divided up amongst the resistors
Voltage stays the same

4. SERIES
PARALLEL
SERIES

5. Resistors in Series…just add up
Resistors in Parallel…add the reciprocals

6. Equivalent Resistance Req = 3W + 1.33W +1W +5W = 10.33W
These two resistors in
parallel can be calculated
as one resistor
= 1W
= 2W
= 4W
= 3W
R2,3 = 1.33W
Req = 3W W +1W +5W
= 10.33W

7. Resistance and Current in the circuit
series
Find the Equivalent
Resistance and Current
in the circuit
= 10W
parallel
= 5W
series
= 10W
I = V/Req
= 40.0V/10W = 4A
What is the current through the 2.0W resistor?
equal resistance…the current divides equally
2A each way

8. Find the equivalent resistance and current
= 40W
= 20W
= 20W
= 40W
Find the equivalent resistance and current
through the 20W and 8W resistors
I = V/Req = 12V/40W = 0.3 A
I through 8W resistor = .15 A

9. What if the resistance is not equal in each resistor?
12V 6W 2W
How much current is going through the 2W resistor?
Calculate the equivalent resistance…
1/Req = 1/6W + 1/2W = .667W-1
Req = 1.5W
Calculate the current in the circuit I = V/Req
I = 8A
The 6W resistor has 3x the resistance than the 2W, so 3x more
current will flow through the 2W resistor… (2W gets ¾, 6W gets ¼)