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I’m a 12th grade student and I’ve had this question for at least a year. This is lenz’s law as I know it: Change in the magnetic flux associated with a coil induces a current, which opposes the cause that is producing it.

My question is, why can’t light cause this change in magnetic flux? It has an oscillating electric and magnetic field. I’ve heard that the the oscillating electric field can oscillate electrons (it’s used in TVs or smth), so why can’t the oscillating magnetic field induce current?

I had a crazy idea that light does actually induce an EMF which opposes the cause (which is light), and this is the reason light slows down in a medium. That is, of course, till reality struck, there would be electric currents everywhere the sun is up. I decided to wait till I get to know light better but I’m really not getting close to an answer.

Shreya
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In simple terms, light is comprised of an oscillating magnetic field which induces an oscillating electric field which induces an oscillating magnetic field. That's how it propagates. This is described by Maxwell's equations in vacuum.

A form of electromagnetic radiation which induces electric currents is when radio waves strike an antenna. The currents then travel in the antenna to a receiver.

However, electric field and electric potential are different from electric currents. You can have an electric field with negligible electric currents. Electric fields cause electric currents depending on resistivity or conductivity. The common equations describing this relationship are:

$J=\sigma E$ or $E = \rho J$

In a perfect vacuum (and let's ignore high energy things like pair production), there are literally no charge carriers so no electric currents. But there is an electric field.

Alwin
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