A spherical shell of radius `R_(1)` with uniform charge q is expanded to a radius `R_(2)`. Find the work performed by the electric forces in this process.

Explanation

To find the work performed by the electric forces when a spherical shell of radius \( R_1 \) with a uniform charge \( q \) is expanded to a radius \( R_2 \), we can follow these steps:

### Step 1: Understand the concept of self-energy
The self-energy \( U \) of a charged spherical shell is given by the formula:
\[ U = \frac{k q^2}{R} \]
where \( k \) is Coulomb's constant, \( q \) is the charge, and \( R \) is the radius of the shell.
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