Electric field performs work on accelerating charges

Steps:

• Uniform field implies constant electric force on the charge, as E is constant.
• Positive charge moves from P to Q in the field's direction, so displacement aligns with force.
• Work by field equals force times displacement (W = qEd, where d is distance along field).
• This work increases particle's kinetic energy, but work occurs regardless of initial speed.

Why D is correct:

• By work-energy theorem, non-zero force along path means positive work done on particle (W = ∫F·dl > 0).

Why the others are wrong:

• A: Uniform field gives constant force, so constant acceleration, not increasing.
• B: Constant field strength means equal force at P and Q.
• C: Kinetic energy increase depends on initial conditions; if starting with high speed at P, it could decrease if opposing initial motion, but work is always done.

Final answer: D