Electric field direction between parallel plates with one earthed

Steps:

• Potential difference is 700 V, with Q earthed at 0 V, so P is at -700 V (lower potential).
• Separation d = 0.05 mm = 5 × 10^{-5} m (from diagram).
• Magnitude E = V / d = 700 / 5 × 10^{-5} = 14 × 10^6 N C^{-1}.
• Direction: from higher potential (Q at 0 V) to lower potential (P at -700 V), so from Q towards P.

Why D is correct:

• Matches E = V/d formula and field direction from positive to negative plate (Q effectively positive relative to P).

Why the others are wrong:

• A and C: Wrong direction; field points from Q (higher potential) to P, not P to Q.
• B: Correct direction but listed as duplicate of D; assume unique in full choices.

Final answer: D