Electric Field and Electric Field Lines

For a charged particle, the electric force is F = qE and acceleration follows F = ma. A proton has positive charge, q = +e, so its force is in the same direction as the electric field. Since its mass is positive, its initial acceleration is also along the field. The opposite direction applies to a negative charge; the acceleration is not zero unless the field itself is zero.

Electric field-line direction is defined as the direction in which a positive test charge would move. Field lines originate at positive charges and terminate at negative charges; therefore, for an electric dipole, the external lines generally run from the positive charge toward the negative charge. Option A is correct. They do not normally begin at negative charge or move outward from both charges, although the complete pattern may curve around the dipole.