Electric Circuit with a breadboard

Your Activity

Use a breadboard to build and test a simple circuit

Material Breadboard LED Resistor, 220-Ω, 1/4-W Battery Connector – 9V Solderless breadboard jumper wire kit Wire Stripper Alligator test leads Battery 9V Solderless breadboard jumper wire kit Multimeter Worksheet: LED circuit on breadboard Worksheet: Multimeter

Create

1. Using the LED circuit on a breadboard, connect all the components together on the breadboard 2. Use a multimeter to measure current and voltage 3. (Bonus) Try another configurations of electric circuit (e.g. using buzzer and motor) on the breadboard

Science Topics

Electrical Engineering, Electricity

What’s going on?

Breadboards are often used for testing new designs since they do not involve soldering. Breadboarding is an essential skill for anyone who plans to design analog and/or digital circuits.

Electric Circuit with a Breadboard Activity Lead Notes

Introduction In this activity, students will learn how to build a circuit that makes a light emitting diode (LED) turn on. They will also

learn what a breadboard is and how electrical engineers use them to design circuits. Finally, they will learn how to

measure voltage and current using a multimeter.

Learning Objectives Build a simple circuit using a solderless breadboard

Explain that engineers use solderless breadboard’s to test circuit design because these circuits may be changed

quickly.

Identify a battery, resistors, LEDs.

Explain what a a) battery b) resistor c) LED does.

Measure the voltage across a circuit element.

Vocabulary Battery: Source of electrical energy

Resistor: Limits energy flow and converts electrical energy into heat

LED Light Emitting Diode: converts electrical energy into light

Breadboard: A solderless board for building electric circuits

Schematic: A diagram of a circuit used by electrical engineers

Multimeter: Device for measuring electrical quantities such as voltage

Materials See the activity description

Preparing Materials Check each multimeter and 9 V battery by turning the knob of the multimeter to the 20 V DC setting and touching the

probes to the battery terminals. The multimeter should read more than 8.7 V. If the multimeter reads less than 8.7 V, try

a second meter. If that still reads less than 8.7 V, try a new battery.

Notes about Materials Ask students to be very careful when using the sharp wire strippers and wire cutters.

Ask students to not play with the insulated wire; they might poke or cut themselves or another student.

Activity Sheet Copy the activity sheet “LED circuit on a breadboard” and distribute one per student (or team).

Conduct Experiment Guide students in conducting the experiment.

Split students into groups of two.

Pass out electronic components. Tell the students not to connect the battery to anything until they are told to

do so!

Walk around and help the students as they work through the activity.

If the LEDs do not light up, change the polarity of the LED by switching the leads. Check to make sure the

students’ circuits are built correctly.

If the battery leads are hard to get into the breadboards, try twisting the strands of the wires to form a firmer

end of the wire.

At the end of the activity, ask the students to put the components back in their original bags.

Collect the components from the students. The batteries go back in the boxes to keep the contacts from touch

something metal and short circuiting.

Background Information

http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_primer-multimeter.shtml

http://techxcite.pratt.duke.edu/docs/TechXcite_Wireless_TVRemote_Act1.pdf

Discuss student observations Source: http://www.teachengineering.org Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado at

Boulder

Electric Circuit with a Breadboard Worksheet: LED circuit on a breadboard

1. Attach the red positive lead from the battery to the power bus, which is the column of sockets near the red line (#1)

2. Connect the resistor to the power bus (#2) 3. Connect the other side of the resistor to one of the rows of five sockets (#3) 4. Connect the long wire from the LED into the same row as the resistor (#4) 5. Attach the other (short) wire from the LED into a different row of five sockets (#5) 6. Insert a jumper wire into the same row of sockets (#6) 7. Insert the other end of the jumper wire into the ground bus, which is the column of sockets near the blue line

(#7) 8. Insert the black wire from the battery into the ground bus. (#8) 9. Attach the battery to the 9-V battery connector. At this point, the LED should light up. If it does not, check the

wiring carefully. 10. Use this circuit to practice with your multimeter. With the circuit closed and the LED "on," measure the voltage

across the resistor by touching the probes to the metal wires on either side of the cylinder (at positions "2" and "3" in the Figure). Measure the voltage across the LED (positions "4" and "5").

Electric Circuit with a Breadboard Worksheet: Using multimeter to measure current

1. Set the multimeter to read "direct current (DC)." Important: Check your multimeter to see where the probe should be plugged in so it reads "current."

2. In order to measure current, you have to open up the circuit and attach the leads from the multimeter so that the current flows through the multimeter. To do this, use jumper wires and wires with alligator clips to add the multimeter to the circuit, as shown in figure above.

3. The white wire is unplugged from the breadboard and attached to the red probe from the multimeter ("1").

4. A jumper wire ("2") is connected to the negative bus.

5. The other end of the jumper wire is attached to the negative lead from the multimeter.

6. The current now flows through the resistor, the LED, the multimeter, and then to the negative terminal of the battery.

7. Depending on your resistor and LED, the current will be measured at around 23 mA (milliamps).

Alternate Circuit

1. Bread Board - Radioshack (Model: 276WBU202/Catalog#: 276-002) or Electronix Express (Part#: 03MB102 - RSR

breadboards/solderless)

2. Rectangular High-Brightness Blue LED Lamp - Radioshack (Model: 276-013/Catalog#: 276-013)

3. 75dB Piezo Electric Buzzer - Radioshack (Model: 273-053/Catalog#: 273-053)

4. DC Motor (1.5-3V) - Radioshack (Model: 273-258/Catalog#: 273-258)

5. Hookup wire 22AWG (Note: Buy "solid" wire, do not buy "stranded") - Radioshack (Model: 278-1221/Catalog#:

278-1221)

6. CR123 3V Battery - Radioshack (Model: 2300695/Catolog#: 23-695)