Technology
How does a transistor work?
A transistor works as a tiny electrical switch or amplifier: a small voltage on one terminal controls a much larger current flowing between the other two. Billions of these switches flipping on and off are what let computers compute.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a transistor works.
Step by step
- 1It's made from semiconductor material (usually silicon) doped to control how it conducts.
- 2A small signal at the control terminal opens or closes the path for a larger current.
- 3As a switch it represents the 1s and 0s of digital logic; as an amplifier it boosts weak signals.
- 4Modern chips pack billions of transistors, some only a few nanometers across.
- 5Its 1947 invention replaced bulky vacuum tubes and launched modern electronics.
Frequently asked questions
- Why are transistors important?
- They are the basic building block of all digital electronics — every computation a processor does is billions of transistors switching.
- What does 'switching' mean for a transistor?
- Turning the controlled current fully on (a '1') or off (a '0'), which is how chips store and process binary information.
- How small can transistors get?
- Leading chips use features just a few nanometers wide — thousands would fit across a human hair — though physics is nearing hard limits.