Foundations of Physical ScienceWorkshop: Electric Circuits

Electric CircuitsCPO Science

Key QuestionsWhat “flow of understanding” provides the necessary foundation for an understanding of electricity?

What kinds of electric circuits can you build?

How does electricity behave?

Light the Bulb!

What needs to happen to get the bulb

to light?

Parts of our Circuits Kit Wooden Board

Wires of various lengths

On/Off switches

Bulbs and holder

Resistors – fixed and variable

Build a simple Circuit Place the bulb in a socket

Use one D cell

Make the bulb light!

Add a switch to conserve D cell energy

Use your finger to trace the path of electricity from one terminal of the D cell to the other terminal

Parts of a Circuit

Wire

Bulb

Battery

Switch

Symbols used for Diagramming

Let’s build on this… Add a second D cell to your circuit,

right next to the first. Be sure to match up positive terminal with negative terminal

Do you notice any difference?

Add a second light bulb to the circuit, keeping only one pathway for electricity to follow

What do you observe now?

Series Circuit

Another way to light two bulbs

Keep two D cells in the circuit

Wire up the 2 light bulbs so that there are two branches or pathways for electricity to follow

What differences do you observe?

Parallel Circuit

Can you explain why the bulbs in a parallel circuit

are brighter?

Water Analogy

Resistance and CurrentInverse Relationship

Voltage

The amount of potential energy that each unit of charge has

ReviewV = voltage, measured in volts

I = current, measured in amperes, or amp

R = resistance, measured in Ohms, symbol

Using the Multimeter to measure Voltage

Battery by itself Battery in a circuit

Using the Multimeter to measure Current

Multimeter completes the circuit

Current in a circuit

Analyze Circuits1 bulb 2 bulbs in

series 2 bulbs in parallel

Total voltage available

Voltage across each bulb

Total current at terminal

Current through each bulb

Why are parallel bulbs brighter?1 bulb 2 bulbs in

series 2 bulbs in parallel

Total voltage available

2.8 V 2.8 V 2.8 V

Voltage across each bulb

2.8 V 1.4 V 2.8 V

Total current at terminal

.12 A .10 A 0.24 A

Current through each bulb

.12 A .10 A 0.12 A