# Electro magnetic Induction problem. Simple one, but check wehre I am wrong.

Electro magnetic Induction problem. Simple one, but plz check wehre I am wrong.

## Homework Statement

A magnet moving down, goes through a coil and exits it below. Plot the graph showing variation of induced emf in coil with time.

## Homework Equations

emf = - Flux/Time

## The Attempt at a Solution

As the magnetic field B increases, emf becomes more and more negative.
Then while leaving, B decreases, emf becomes more and more positive.

Hence

The emf is first negative, forms a V shape in the negative emf region and then an inverted V in the positive emf region when it leaves.

The emf is first positive ... in other words just the opposite of what I said.

Where did I go wrong ?

Related Introductory Physics Homework Help News on Phys.org
From what two points are you measuring the emf?

From either ends of the coil

Isn't the "B" in this system a vector?

(Those tricky vectors...) ~A137

Ya. But how will that matter?

I think I get it now.
Initially B and Area vectors are antiparallel, so flux is negative. Hence, the induced emf is positive.