Model answers

[DiMmY]

Q: Explain why the input of a transformer must be AC rather than AC.


Rather than DC I think you mean =P

IMHO we're more likely to see a Q asking what the double slit experiment proves, rather than why the middle is bright.

[Ken]

why are electromagnets preferred over permanent magnets?

[Collin Li]

why are electromagnets preferred over permanent magnets?

In a transformer, they are critical, as the magnetic field is controlled by electricity. This allows one coil to cause changes in flux, merely by electrical input, that influence the other coil to induce current. Otherwise, induction with a permanent magnet would require physical movement (as opposed to electrical input) of the magnet, to cause a change in flux.

[onlyfknhuman]

why are electromagnets preferred over permanent magnets?

In a transformer, they are critical, as the magnetic field is controlled by electricity. This allows one coil to cause changes in flux, merely by electrical input, that influence the other coil to induce current. Otherwise, induction with a permanent magnet would require physical movement (as opposed to electrical input) of the magnet, to cause a change in flux.

Thats in terms of transformers though yeah? so generally its preferred because you can easily turn it on and off, and increase the strength and area of the magnetic field to your desire through increasing the current through it or inserting a soft iron core. yeah?