Question

A point charge +Q is placed at point O as shown in the figure. Is the potential difference $V_{A}-V_{B}$ positive, negative or zero?

Answer 1

it must be positive

Answer 2

The direction of electric field for positive charge is in the outward direction and perpendicular To the plane of infinite sheet direction of electric field for negative charge if i to the plane of infinite sheet direction of electric field for negative charge is in the inward  Direction and perpendicular to the sheet