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How does a transistor work?

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Quick answer

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. It's made from semiconductor material (usually silicon) doped to control how it conducts.

Step by step

  1. It's made from semiconductor material (usually silicon) doped to control how it conducts.
  2. A small signal at the control terminal opens or closes the path for a larger current.
  3. As a switch it represents the 1s and 0s of digital logic; as an amplifier it boosts weak signals.
  4. Modern chips pack billions of transistors, some only a few nanometers across.
  5. Its 1947 invention replaced bulky vacuum tubes and launched modern electronics.

People also ask

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.
How does a transistor work?
A small voltage at its control terminal switches or amplifies a larger current flowing through it.
How many transistors are in a modern chip?
Often billions, each far smaller than a speck of dust.