The distance of point $$A\left( {\sqrt 2 ,\sqrt 2 } \right)$$ from the origin,

$$OA = \left| {\overrightarrow {{r_1}} } \right|$$

$$ = \sqrt {{{\left( {\sqrt 2 } \right)}^2} + {{\left( {\sqrt 2 } \right)}^2}} $$

$$ = \sqrt 4 = 2$$

The distance of point $$B(2,0)$$ from the origin,

$$OB = \left| {\overrightarrow {{r_2}} } \right| = \sqrt {{{\left( 2 \right)}^2} + {{\left( 0 \right)}^2}} = 2$$ units.

Now, potential at $$A,$$ $${V_A} = {1 \over {4\pi { \in _0}}}.{Q \over {\left( {OA} \right)}}$$

Potential at $$B,$$ $${V_B} = {1 \over {4\pi { \in _0}}}.{Q \over {\left( {Ob} \right)}}$$

$$\therefore$$ Potential difference between the points $$A$$ and $$B$$ is zero.