- #1
Aurelius120
- 164
- 16
- Homework Statement
- Two non conducting hemispherical surfaces of uniform charge density ##\sigma## are placed on horizontal surface. Find maximum compression in each spring if both surfaces are touching each other initially
- Relevant Equations
- Force on charge in an electric field=##qE##
Spring Force=##kx##
So I know I have to equate force on a hemispherical shell with spring force to get value of compression but I can't find the force on the hemispheres
Some places that do have the solution use the formula :
$$\text{Field of non-conducting hemispherical shell= } \frac{\sigma}{2\epsilon_○} $$
This is also the formula for infinite sheet.
Then the net charge on other sphere is ##\sigma \pi r^2##
Then Option-C is correct answer
However I have two problems:
1. I couldn't derive the formula despite trying. It also doesn't makes sense that the field is uniform. The shell is made up of rings and rings have non-uniform fields. How do I understand and derive this?
2. The net charge on other hemisphere should be ##\sigma×2\pi r^2## Or ##\sigma×3\pi r^2##?