# How step-up / step-down transformers work considering that you cannot create or destroy electrons?

Transformers transform a high-current, low-voltage flow into a low-current, high voltage flow. But since current is dependent on the number of electrons and voltage is dependent on the energy each electron has, and you cannot turn energy into an electron or turn an electron into energy, how do the transformers create a higher current flow from a low current flow?

• How do generators work if electrons can't be created? Apr 29 '18 at 23:50
• Watch this demonstration of Faraday's law. Go completely through the entire video starting around 5 minutes into it.
– jonk
Apr 30 '18 at 0:09
• Apr 30 '18 at 9:24

Electrons aren't created or destroyed, they just move around.

Have a look at a diagram of the transformer: (from Wikimedia Commons)

Electrons get pushed into the red coil, and out the other end of the red coil. This causes different electrons to be pulled into the blue coil, and pushed out the other end of the blue coil. At no point are electrons created or destroyed.

• But in order for more current to flow wouldn't there need to be more electrons? Apr 30 '18 at 0:12
• @user180969 More electrons go through the secondary coil, if that's what you mean. We don't care whether they're new electrons, or the same ones going in a loop after they went through a lightbulb. (Doesn't going faster mean you need bigger wheels?) Apr 30 '18 at 0:28
• @user180969 No. Any conductive material has a fixed number of electrons. Pumping water around a small loop you have a fixed amount of water, it doesn't matter how quickly you pump it or how high the pressure is you don't create or remove water. Apr 30 '18 at 1:32
• You don't need more bicycle chain when you pedal faster, either. Apr 30 '18 at 1:50
• @immibis Hey ! Electrons can be destroyed ! If this is nuclear physics or astronomy. Apr 30 '18 at 9:30

Current is dependent on the number of electrons, but also on their speed. A transformer (or a generator, for that matter) simply accelerates the electrons that are already in the copper (or aluminum, or whatever metal you choose to make the wire out of--usually copper though) to higher speeds.

This is a simplified explanation, but it gets the point across and isn't exactly wrong, either.

Current, I = dQ/dt
VI primary = VI secondary if Mutual Coupling = 1 and Losses =0
Vs/Vp = n turns ratio (s/p)
Ip/Is = n turns ratio (s/p)

So when you step up voltage you also step down current.

Q is the charges being bumped around the current loop, due to the voltage or the Electromotive Force (EMF).

dQ/dt is the measure of current or flow of electrons.

This is a rather simplistic approach. Let's say a piece of copper weighs 10 grams. How many atoms are there in it?

1 mole is 63.5 grams of copper and, using avogadro's number (6.02 x10$^{23}$) we get 9.48 x 10$^{22}$ atoms. Each one of those atoms can contribute an electron to be used by current flow.
1 amp is an electron flow of 6.25 x10$^{18}$ electrons per second i.e. a utilization of the free electrons of 0.00659%.