Series vs. Parallel Circuits *Characteristics of these circuits

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

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

Electricity in Analogies

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

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

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

RESISTANCE BEHAVES DIFFERENTLY IN SERIES VERSUS PARALLEL CIRCUITS

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

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 + 1 + 1 …. 1 Rt R1 R2 R3 Rn

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

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