Calculate the height of potential barrier for a head on collision of two deuterons. The effective radius of deuteron can be taken to be 2fm. Note that height of potential barrier is given by the Coulomb repulsion between two deuterons when they just touch eachother.

Explanation

To calculate the height of the potential barrier for a head-on collision of two deuterons, we will follow these steps:

### Step 1: Determine the effective radius of a deuteron.
The effective radius of a deuteron is given as 2 fm (femtometers). We need to convert this into meters.

\[ \text{Effective radius} = 2 \, \text{fm} = 2 \times 10^{-15} \, \text{m} \]
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