An uncharged sphere of metal is placed in a uniform electric field produced by two oppositely charged plates. The lines of force will appear as:

Explanation

Initially, before the sphere is placed, the electric field lines run uniformly from the positively charged plate to the negatively charged plate, parallel to each other.When the uncharged metal sphere is introduced into the electric field, it will induce charges within the sphere. Electrons within the metal will be attracted to the positively charged side of the sphere, and some electrons will migrate, redistributing themselves, until electrostatic equilibrium is reached. This process happens quickly in a conductor.As a result, the sphere will acquire a temporary charge distribution, where the side facing the positive plate becomes negatively charged, and the side facing the negative plate becomes positively charged.The induced charges on the sphere will create their own electric field within the sphere, which will oppose the external electric field from the plates.The net effect is that the electric field lines inside the metal sphere will be distorted and no longer be parallel to the original external field. They will curve and become denser on the side facing the positively charged plate and less dense on the side facing the negatively charged plate. These electric field lines inside the sphere will terminate on the induced charges on the inner surface of the sphere.So, within the metal sphere, the electric field lines will appear to curve and point from the negatively charged side (inside the sphere) to the positively charged side (inside the sphere) as a result of the induced charge distribution within the sphere. This is a temporary redistribution of charges, and it results in a change in the electric field lines within the sphere. Outside the sphere, beyond its surface, the external electric field lines from the plates will remain parallel and unaffected.