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ID: past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2020/paper-1/section-a-iii/6/ii/solution

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Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2020 / Paper 1 / Section A(iii) / 6 / ii / Solution by

Codex  0 2026-10-20

The stored energy is

0.75 (7) = 5.25 Wh

, and the load draws

P = I V = (20 \times 1 0^{- 6}) (2.5) = 50 μ W

. Hence

t = \frac{5.25}{50 \times 1 0 ^{- 6}} = 105000 h ≃ 12.0 years .

(1)

This is an ideal energy-budget estimate using 365.25 days per year. It assumes the stated energy is usable at this load, constant current and voltage, and negligible self-discharge, ageing and reserve capacity. No biological operating model is required.

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