# Motional EMF

## Homework Statement

http://img854.imageshack.us/img854/3980/33288207.th.png [Broken]

## The Attempt at a Solution

http://img813.imageshack.us/img813/1065/60582408.th.png [Broken]

$$\varepsilon = IR$$

$$\varepsilon = -\frac{d \Phi}{dt}$$

$$\Phi = BA$$

$$-\frac{d \Phi}{dt} = -Bl\frac{dx}{dt} = -Blv$$

So

$$\frac{-Blv}{R} = I$$

$$\frac{-IR}{Bl} = v$$

Now I plug in and solve, is that right or did I underestimated this question completely?

Last edited by a moderator:

Actually I just realize I assumed the current is running counter clockwise..

Actually never mind, by Lenz' Law the direction is counter clockwise for the current

Oh wait it says speed, so

$$\left | \frac{-lR}{Bl} \right | = |\vec{v}|$$

I'll just trust myself...*crickets*

SammyS
Staff Emeritus