TITLE: Why does electromagnetic induction happen?
QUESTION [2 upvotes]: What is the reason behind electromagnetic induction? Why is a current induced in a changing magnetic field?
I am only a highschool sophomore and therefore not well versed with Lorentz force or anything of the sort. I do know about flemings left hand rule though, but not any equations. I am trying to have an intuitive understanding of what is happening.. Please explain using the simplest terms.

REPLY [2 votes]: We are used to thinking of magnetic and electric fields as separate things that are different from each other, but this is not the case. There is a single field called the electromagnetic field and the things we call electric fields and magnetic fields are just different ways of viewing the electromagnetic field.
Specifically we only see a purely magnetic field or a purely electric field when we are stationary relative to the field and the field is constant so it doesn't change with time. In all other conditions the electromagnetic field appears to us as a mixture of electric and magnetic fields.
And this is the reason we see electromagnetic induction. Suppose we have a charge and an electromagnetic field that is moving relative to that charge. A moving EM field always appears as a mixture of a magnetic and electric fields, and the electric field part of the EM exerts a force on the charge and makes it accelerate. The acceleration means the charge starts moving, and a moving charge is a current.
Alternatively if the EM field is changing with time then again it always looks like a mixture of a magnetic and electric field, and the electric field exerts a force on charges and causes a current.
This is about as far as we can go if you want an explanation in simple terms, and to get any farther requires us to start exploring special relativity. In SR we describe fields like the EM field as four dimensional objects. For example the EM field is described by the four dimensional object called the electromagnetic tensor. The electric and magnetic fields we are used to in everyday life are in effect three dimensional views of the four dimensional EM field. When the field moves relative to us this changes our view of the 4D EM field and we see different electric and magnetic fields.
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