Find the electric field potentail and strength at the centre of a hemisphere fo raidus `R` ahcged uniformly with the the surface density `sigma`.

Explanation

To find the electric potential and electric field strength at the center of a uniformly charged hemisphere of radius \( R \) with surface charge density \( \sigma \), we can follow these steps:

### Step 1: Consider the Hemisphere
We have a hemisphere of radius \( R \) uniformly charged with a surface charge density \( \sigma \). The center of the hemisphere is the point where we want to find the electric potential and electric field strength.

### Step 2: Elemental Charge
We can consider an infinitesimal ring at an angle \( \theta \) from the vertical axis. The thickness of this ring is \( R d\theta \), and the radius of the ring at this angle is \( R \sin \theta \).

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