पृथ्वी के पृष्ठ से जरा ऊपर वातावरण में साधारणतया उपस्थित असत विद्युत क्षेत्र का परिमाण \(150\; N / C\) के लगभग है जिसकी दिशा पृथ्वी के केन्द्र की ओर अन्तरमुखी है। यह पृथ्वी द्वारा वाहक परिणामी पृष्ठ आवेश देगा : [दिया है \(\epsilon_{ o }=8.85 \times 10^{-12} \;C ^{2} / N - m ^{2}\), \(R _{ E }=6.37 \times 10^{6}\; m\) ]

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.