# Magnetic sphere in electrolyte

1. Oct 24, 2005

### sitisuhanis

If you have a metal sphere of the order of a say, few micrometers in diameter, and you put it in an electrolyte solution - what would you expect to happen when a current is passed through that solution? I am referring here to charges on the surface of the sphere.
Cheers!

2. Oct 24, 2005

### P-man

Well the sphere would get electrically charged?

3. Oct 25, 2005

### somasimple

The sphere will be possibly in the circuit but charges will go once the current will stop.

4. Nov 4, 2005

### P-man

You want this sphere to continue being charged once the current has stopped flowing?

5. Nov 5, 2005

### rachmaninoff

The applied voltage would create an electric field across the microsphere. Since it's a good conductor, electrons/holes in the metal would re-arrange to try to cancel the electric field. Ions in solution would be attracted to these charges, sheilding their effect.
Code (Text):
electrode                                                      electrode
+    ------> current, +ion motion                              -
+   <------  -ion motion                                      -
+                                                             -
+              +             -                                 -
+            +     -     +                                   -
+                -   ball  +     - free ions               -
+          +     -         +                                 -
+                  -      +       -                         -
+            +                 -                              -
(note the distinction between the current ions, and the "stationary" ions shielding the sphere)
These are relatively small effects; consider that you have only 2-3V across several cm of electrolyte (small electric field). Ignoring the ion current (which has no not charge), this can be treated as a simple problem of electrostatics: a metal sphere surrounded by a dielectric, in an applied E field - you can solve this with an expansion in spherical harmonics.

Last edited by a moderator: Nov 5, 2005
6. Nov 6, 2005

### P-man

And if you set that ball in motion in a strait line, which way would it bend? Or would the elctric charge not affect it?