1. Series vs. Parallel Circuits
*Characteristics of these circuits

2. What is resistance? What does the word “resistance” make you think of?
What do you think it does in an electric circuit?

3. Think of American Gladiators...
The contestant is the “electron” trying to flow through the circuit, when he encounters “resistance” and it slows him down...

4. Electricity in Analogies

5. Electricity in Analogies
Voltage = potential / pressure = amount of water in the jug
Current = flow of electricity = water flow
Resistance = something that slows down current = size of the spout

6. Important Things to remember...
Quantity
Symbol
Unit
Voltage V
volts (V)
Current I
Amperes (A)
Resistance R
Ohms (Ω)

7. Ohm’s Law Quantity Symbol Unit Formula Measured with Voltage V
volts (V)
V = I x R
Voltmeter
Current I
Amperes (A)
I = V / R
Ammeter
Resistance R
Ohms (Ω)
R = V / I
Ommeter

9. RESISTANCE BEHAVES DIFFERENTLY IN SERIES VERSUS PARALLEL CIRCUITS

10. Ohm’s Law What is the law? Analogy I = VR
This means that current is dependent on how much voltage is slowed down by resistance
I = V R
Contestant on gladiators
Water flow

11. Calculating Total Resistance
Calculating total resistance in series circuits (CURRENT GOES THROUGH EACH RESISTOR):
Rt = R1 + R2 + R3 …. Rn
Calculating total resistance in parallel circuits (CURRENT DOES NOT GO THROUGH EACH RESISTOR):
1 = …. 1
Rt R1 R2 R3 Rn

12. Sample Question 1 + Electric Drawings
Four 1.5 ohm lamps are connected in series and connected to a 3 volt battery. Calculate the total current in the circuit.
i. State the givens
ii. Write the formula in its proper format
iii. Show your work
iv. Write a sentence

13. Sample Question 2 + Electric Drawings
A 10 ohm, 20 ohm, and 100 ohm resistors are connected in parallel. They are then connected to a 3V battery. Calculate the total current.
i. State the givens
ii. Write the formula in its proper format
iii. Show your work
iv. Write a sentence