Question

Electric potential of a point in an electric field is defined as the work to be done to move a unit positive charge from infinity to that point. What does infinity mean here?

Answer 1

Here infinity means where the effect of electric field is negligible or zero. Suppose U have a magnet placed on the table and trying to attract it from another magnet standing 20 meters apart the magnet will not move because the range of magnetic field is not up to that point. Similar in case of electric field a small charge placed in one room can’t be attracted if electric field is set in your school lab.