A point charge Q is placed at the origin of the coordinate system. What is the electrostatic energy within an annular spherical region, with centre at origin and inner and outer radius R and 2R respectively.

Explanation

To find the electrostatic energy within an annular spherical region with a point charge \( Q \) placed at the origin, we can follow these steps:

### Step 1: Define the Problem
We have a point charge \( Q \) at the origin, and we need to calculate the electrostatic energy in the annular region between the inner radius \( R \) and the outer radius \( 2R \).

### Step 2: Understand the Concept of Capacitance
The capacitance \( C \) of a spherical capacitor is given by the formula:
\[
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