Idea 2of 4Builds onTurns set the voltsWatts in the wire
The lever, not the amplifier
Twenty times the turns, twenty times the volts. The power?
Today you'll discover
- why the volts can go up but the power cannot
- what the turns ratio must do to the current
- the name of the device, and what it really trades
Think firstOne turn to twenty: 12 V in. What comes out?
12 V into one turn; 20 turns out give 240 V. Does the secondary also give 20 times the power?
Decide first, then press Next. Compare the watts on the two sides.
An iron ring with a one-turn coil on the left and a twenty-turn coil on the right. After a prediction, a dashed changing field appears in the core, then the secondary's volts, then the amps and watts on both sides, equal. The last step turns it round into a step-down and asks what comes out.
See the whole ideathe big idea and the key word, in one place
The big idea
A transformer trades volts for amps; power is unchanged.
Easy to get wrongStepping up the voltage does not step up the power. Vp Ip = Vs Is always. What a transformer buys is the choice of HOW to carry the same power.
Key word
- transformer
- two coils on an iron core; an alternating current in the primary induces a voltage in the secondary in the turns ratio, Vs ÷ Vp = Ns ÷ Np, with power unchanged
About this modelVs ÷ Vp = Ns ÷ Np, and Vp Ip = Vs Is: a lever, not an amplifier. AC only, because only change induces.
Vs ÷ Vp = Ns ÷ Np, and Vp Ip = Vs Is: a lever, not an amplifier. AC only, because only change induces.
Ready to use it?
- Find the secondary voltage and current from the turns ratio and the power.