⚡ Transformer Mutual Induction Lab

About this simulation

A transformer moves electrical power from one circuit to another with no wires touching. An alternating current in the primary coil builds a changing magnetic field that a laminated iron core channels almost entirely into the secondary coil, where it induces its own alternating voltage — Faraday's law of electromagnetic induction at work.

How it works

• Magnetic flux — the glowing pulses travelling around the core are the shared flux Φ that links both coils; their brightness swells and reverses every half-cycle, just like the driving current.
• Turns ratio — the secondary voltage equals the primary voltage times Nₛ/Nₚ. More secondary turns than primary turns steps voltage up; fewer steps it down.
• Ideal power balance — with a load connected, power in ≈ power out, so the side with more turns and higher voltage carries proportionally less current.
• With the secondary circuit open, almost no current flows in either coil — only a small magnetising current sustains the flux.

Controls

• Primary turns (Nₚ) — number of windings on the input coil.
• Secondary turns (Nₛ) — number of windings on the output coil; sets the turns ratio.
• Input voltage (Vₚ) — the AC voltage driving the primary coil.
• AC frequency — how fast the driving current alternates (slowed down for visibility).
• Secondary circuit — toggle between an open circuit and a resistive load to see current and the lamp respond.

Did you know?

Grid transformers step voltage up to hundreds of kilovolts for long-distance transmission — high voltage means low current for the same power, which shrinks resistive losses (I²R) in the cables — then step it back down near homes and factories, all without a single moving part.