Circuits Lesson

Circuits and Ohm's Law

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Circuit Symbols

• Battery

• Bulb

• Switch

• Resistor

Types of Circuits

• Series Circuits

• Parallel circuits

Open Ended

What is the difference between a parallel circuit and a series circuit?

Series circuits

• All elements in the circuit are in one loop

• Every electron flow through every element

• If one bulb burned out, the rest would also go out

Let's build a simple circuit with one bulb.

You will need a bulb, a battery, and two wires.
After you completed a simple circuit with one bulb, your group can add another bulb.
What happens to the brightness when multiple bulbs are added?
What happens when one bulb is removed?

Parallel circuits

• There are several pathways or loops through the circuit

• Electrons flow through just one of those pathways

• If one bulb burned out, the rest of the bulbs would still glow

Let's build a simple parallel with two bulbs.

You will need 2 bulbs, a battery, and four wires.
After you completed a simple parallel circuit with two bulbs, your group can add another bulb.
What happens to the brightness when multiple bulbs are added?
What happens when one bulb is removed?

Multiple Choice

What kind of circuit is this?

• series

• parallel

Multiple Choice

what kind of circuit is this?

• parallel

• series

• partial

• open

Multiple Choice

This is an example of a ______ circuit

• Series

• Parallel

• Open

• Partial

Multiple Choice

What is the type of circuit that stops working when one bulb goes out?

• A broken circuit
• Parallel Circuit
• Series Circuit
• A metal circuit

Multiple Choice

In a parallel circuit if one of the light bulbs burns out the rest _________.

• stop the flow of electricity

•  can still light up

•  will go out

• of the light bulbs burn out also

Ohm's Law - V=IR

• Shows the relationship between current, voltage, and resistance

• V is for VOLTAGE (volts)

• I is for CURRENT (amps)

• R is for RESISTANCE (ohms)

Voltage (V)

• Comes from the battery or another voltage source

• The "push" that moves electrons around the circuit

• Think of it like a water pump - without the pump, the water would just sit in the pipe and not move anywhere

Current (I)

• Electrons in the circuit flowing or moving around the circuit

• Measured in amps

• When electrons move faster, the current is greater

• Like the water flowing through a pipe

Resistance (R)

• Makes it harder for electrons to flow through the circuit

• Measured in Ohms

• Kind of like friction or sand that slows the water in the pipe down

Example 1

• There are 4 amps of current flowing through a circuit with 2 ohms of resistance. How much voltage did the battery provide?

Example 2

• There are 4 amps of current flowing through a circuit with a 12 volt battery. How much resistance is in the circuit?

Example 3

• How much current would flow through a circuit with 25 ohms of resistance and 100 volt battery?

Multiple Choice

What is the resistance of a lightbulb that experiences 9 Volts and 3 amps of current?

• 1/3 ohms

• 3 ohms

• 27 ohms

• 9 ohms

Multiple Choice

What is the current in a circuit with 6 ohms of resistance and a battery containing 24 Volts?

• 1/4 A

• 144 A

• 4 A

• 0.4 A

Multiple Choice

What is the voltage of a circuit with 4 ohms of resistance and 3 amps of current?

• 12 V

• 21 V

• 4/3 V

• 3/4 V