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Profiles of Scientists



Lesson 3

Transistors in Your Life: A Transistor Hunt


In this lesson, students search for transistor-based devices at school. They use the results of their search to explain the significance of the transistor in their lives.


• To find examples of transistors in school

• To realize the number and significance of transistors in everyday life


A transistor is a tiny device that either switches electric current on and off or amplifies an electric current. The original transistors were small cylinders, a bit larger than a pencil eraser. Over the years, scientists and engineers have been able to make transistors tinier and tinier. With the invention of the integrated circuit, or microchip, in which thousands or millions of transistors are deposited on a piece of silicon, transistors have become microscopic.


Transistors are the main component of the microchips used in computers. Computers operate on a binary system, which uses only two digits: 0 and 1. In a computer microchip, transistors act as switches, letting current through to represent the binary digit 1, or cutting it off to represent 0. Every kind of information (words, numbers, pictures, etc.) are converted into strings of 1s and 0s.

Today many household appliances including televisions, VCRs, stereos, telephones, refrigerators, washers and dryers, microwave ovens, alarm systems, and fax machines have chips built into them. The chips allow the devices to process great volumes of information and provide the user with exactly the information desired, from identifying the name and phone number of a caller to playing and replaying the chorus of the latest hip-hop release.

Transistors are also found in pacemakers, hearing aids, cameras, calculators, and watches. Most of these devices draw their power from tiny batteries. Most spacecraft also rely on microchips, and thus transistors. The transistor is truly the "nerve cell" of the information age.


To introduce the importance of the invention of the transistor, help students visualize its impact on the design of computers. If possible, show students a vacuum tube. If a vacuum tube is not available, you might use a 25-watt light bulb as a model for the vacuum tube. Indicate that ENIAC (Electronic Numerical Integrator and Computer), built in 1946 and considered the first of the modern generation of electronic computers, used about 18,000 vacuum tubes. The machine needed a lot of power to run and produced a tremendous amount of heat. (The air conditioning equipment needed to cool ENIAC was enough to cool the Empire State Building.) What’s more, ENIAC occupied a great deal of space—occupying over 150 square meters of floor space and standing 2.5 meters tall. Let students measure and calculate how many classrooms would be needed to fill the space taken up by ENIAC.

If students have not yet viewed the video Transistorized!, show the first ten minutes including Ira Flatow describing the vacuum tube and its drawbacks and discussing Mervin Kelly’s vision for a solid state amplifier.


Prepare students for the project by asking: Where can you find transistors? Where are they most common? What’s the big deal about transistors anyway? Explain that they will be able to answer these and other questions in this project as they search for transistors all around them.


After teams have discussed and presented their findings, hold a class discussion about the prevalence of transistors in our lives. At a minimum, students should be able to

• list everyday activities that are monitored or controlled by transistors.

• identify appliances and devices that rely on transistors and which greatly affect our quality of life.

• provide evidence to support or refute the claim that the transistor is the most significant invention of the 20th century.

LESSON 3 Activity

What You’re Going To Do

You’re going to work in teams to hunt for transistor-based devices at your school. Then you’ll use the results of your search to explain why the transistor is so significant.

What You’ll Need

• reference materials about transistors and transistor devices including information from the Transistorized! web site:

How To Do It

1. In your team, use reference materials to become familiar with the wide range of devices that use transistors. You might want to make a list of these devices to refer to on your hunt.

2. Search the school for electronic devices that use transistors. List the devices. If you find a particular device in more than one place, note each location on your list. If you are not sure if the device relies on transistors, use your reference materials to check. Make a note of any electrical devices you find that do NOT rely on transistors.

3. Discuss your list with your team. Make a three-column chart like the one below. In the first column, identify the five devices your team thinks affect you the most. In the second column, tell why each device is important to your life. In the third column, describe how your life would change without each device.

4. Compare and contrast your team’s chart with the charts of other teams. What devices did they identify that you did not? Which did they find most important that you did not? If necessary, revise your list to show devices you missed or to eliminate devices that do not contain transistors.

What Did You Find Out?

1. How did your top-five devices compare to those of your classmates? Which devices were most often identified by the class?

2. Explain why the transistor is considered the most significant invention of the 20th century.


Try This!

  • Write an essay on the electronic device that most changed your life.
  • Research the size of a modern, individual transistor. Find out how such a small object is manufactured and manipulated.
  • Hold a "Day Without Transistors." Give up as many electronic devices as possible for one day. Then discuss how your life was different during that 24-hour period.
  • How small can a transistor become? Is there a limit? Explore the ongoing research into these questions and report your findings.
  • Work in groups to design an electronic device that solves an everyday problem.

Lucent These educational materials are made possible by a grant from The Lucent Technologies Foundation and may be duplicated for educational non-commercial use.

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