Magnetic fields

[map7s]

Homework Statement

An artery has an inside diameter of 3.20 mm and passes through a region where the magnetic field is 0.065 T.
If the voltage difference between the electrodes is 155 µV, what is the speed of the blood?

Homework Equations

V=kq/r E=kq/r^2 v=E/B

The Attempt at a Solution

I know that I have to ultimately use the last equation to find out velocity, but I need to first find out E. I tried using the second equation, but I am not quite sure as to what I'm doing wrong. First of all, is that right equation? For q, am I supposed to use the charge of an electron/proton? is r supposed to be entire diameter or should I divide it half?

 

[robb_]

Remember that V is a scalar and E is a vector. They are related somehow or another...

 

[turdferguson]

There is a simple equation for induced emf that applies here

 

[map7s]

In my calculations I wasn't able to include V, but I know that I should. However, I don't know how the two relate to each other in an equation....Also, I don't think that I've learned about emf...