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📘 How Transformers Work

A transformer changes voltage with no gears, pistons, or wire connecting its two windings. Alternating current creates changing magnetic flux in a core, and that flux induces voltage in the secondary.

4
lessons
~20 min
to learn
Adults
level
Start the course →

What you’ll learn

  1. How induction sets voltageExplain how changing current and the turns ratio induce and set voltage in a separate secondary winding.Changing magnetic flux couples two windings through a core; the turns ratio sets the secondary voltage while current changes in the opposite direction.
  2. Why the grid steps upConnect high-voltage transmission and lower-voltage distribution to transformer operation.The grid steps voltage up to reduce current and line heating, then steps it down in stages for local use.
  3. Inside a real transformerIdentify the roles of the magnetic core, laminations, insulation, and cooling.Real transformers manage flux, heat, insulation stress, and material losses so the induction process remains reliable.
  4. What transformers cannot doExplain why conventional transformers need changing current and summarize their limits.Steady DC cannot sustain secondary induction in a conventional transformer; electronic converters create changing waveforms first.

Questions this course answers

What determines the ideal voltage ratio of a transformer?

For an ideal transformer, Vs/Vp equals Ns/Np.

Why does the grid step voltage up before long-distance transmission?

For a given power, higher voltage means lower current, reducing I squared R losses.

What happens to current when an ideal transformer steps voltage up?

Approximate power conservation requires voltage and current to trade in opposite directions.

Why does a conventional transformer need AC or another changing waveform?

Induction depends on changing magnetic flux; steady DC cannot sustain it after the initial change.

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