1. Circuits

2. DO NOW With a partner, collect
One battery
One wire
One lightbulb
Working with your partner at your desk and your knowledge of circuits, make the lightbulb light up.

3. Hint #1

4. Hint #2
One side of the wire in the lightbulb touches the metal part of the light bulb. The other side of the wire is connected to the bottom.

5. Solution

6. Series Circuits 𝑉 𝑇 =𝐼 𝑅 𝑒𝑞 𝑉 1 =𝐼 𝑅 1 𝑉 2 =𝐼 𝑅 2 Rules 𝑉 3 =𝐼 𝑅 3
You will also have to use Ohm’s Law, but you can NOT cross contaminate!
𝑉 𝑇 =𝐼 𝑅 𝑒𝑞
Totals
𝑉 1 =𝐼 𝑅 1
Only R1
𝑉 2 =𝐼 𝑅 2
Only R2
Rules
𝑉 3 =𝐼 𝑅 3
Only R3
If you add a 4th resistor, the total resistance will INCREASE which means the total current will DECREASE. Total voltage is constant

7. Series Circuits
If the current through R1 is 4 amps, what is the current through
R2?
R3?
The total current coming out of the battery?
If R1 is 3Ω, R2 is 7Ω, and R3 is 4 Ω, what is the equivalent resistance of the circuit?
What is the potential drop across R1 R2 R3
What is the total potential difference supplied by the battery?
Rules

12. Req will ALLWAYS be less than the smallest resistor in the circuit!
Parallel Circuits
You will also have to use Ohm’s Law, but you can NOT cross contaminate!
V= 𝐼 𝑇 𝑅 𝑒𝑞
Totals
Rules
𝑉= 𝐼 1 𝑅 1
Only R1
𝑉= 𝐼 2 𝑅 2
Only R2
V= 𝐼 3 𝑅 3
Only R3
If you add a 4th resistor, the total resistance will DECREASE which means the total current will INCREASE. Total voltage is constant
Req will ALLWAYS be less than the smallest resistor in the circuit!

13. Parallel Circuits Rules
If the potential difference over R1 is 12 volts, what is the potential difference
R2?
R3?
The total potential difference supplied by the battery?
If R1 is 3Ω, R2 is 7Ω, and R3 is 4 Ω, what is the equivalent resistance of the circuit?
What is the current through R1 R2 R3
What is the total current coming from the battery?
Rules