Changing the Reference Point of a Potential Line Integral

Changing the reference point accounts to adding a constant $K$ that is equivalent to the field tracing out the path from the old reference point $O$ to the new reference point $O^{\prime }$

$$V^{\prime }(r)=-\int \_{O^{\prime }}^{r}E\cdot dl=-\int \_{O^{\prime }}^{O}E\cdot dl-\int \_O^{r}E\cdot dl=K+V(r)$$