Net force on dipole in uniform field is zero

Steps:

• The dipole has equal and opposite charges, so forces from the uniform vertical electric field are equal in magnitude but opposite in direction.
• These forces cancel, resulting in zero net force on the dipole.
• With no net force, the dipole's velocity remains unchanged in both components.
• Initial velocity is purely horizontal and constant, so no vertical component develops.

Why B is correct:

• In a uniform field, the net force on an ideal dipole is zero (from superposition of forces on charges), preserving constant horizontal velocity and zero vertical velocity.

Why the others are wrong:

• A: Vertical component does not increase, as no net vertical force acts.
• C: Horizontal component does not increase, as field is vertical and exerts no horizontal force.
• D: Neither component changes; horizontal stays constant, vertical remains zero.

Final answer: B