Consider a finite insulated, uncharged conductor placed near a finite positively charged conductor. The uncharged body must have a potential :

The potential of the uncharged conductor is determined as follows:

Potential relative to Infinity: Since it is placed in the field of a positive conductor, work is required to bring a test charge from infinity to its location, making its potential more than at infinity.

Potential relative to the Charged Conductor: Because potential decreases with distance from the source, its potential is less than that of the charged conductor.

Therefore, the uncharged body must have a potential less than the charged conductor and more than at infinity.