# What is the magnitude of charge inside the box

1. Sep 7, 2006

### eltel2910

have a box that is 4.15 cm on each side. Using a probe I measure on two opposite sides of the box and find a nearly uniform, inward-oriented, perpendicular component of the field with the magnitude of 18.3 N/C. What is the magnitude of charge inside the box?

2. Sep 7, 2006

### Staff: Mentor

Hint: Use Gauss's law.

3. Sep 9, 2006

### eltel2910

like this?

so do I set it up like: 18.3 = q/(2Eo). Solving for q and then that would give me one unit and then I would multiply by the volume of the cube (.00414^3)?????

4. Sep 10, 2006

### Staff: Mentor

To find the charge within the box using Gauss's law, first calculate the flux through each side of the box. The total flux will allow you to calculate the total charge. See this for more on http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gaulaw.html" [Broken].

Is the field uniformly inward on all sides of the box? Or just two?

Last edited by a moderator: May 2, 2017
5. Sep 10, 2006

### eltel2910

Got it

Got it Thanks Doc.