EasyAssistant Engineer (Electrical), Class-2, Road and Building Department2025✓ Editorially verified

A new renewable energy system is designed to harvest energy from wind. The total energy required to build the system is 240 kJ. The energy yield ratio of the system is 14:3. What will be the total energy provided by the system over its lifetime?

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Answer & Explanation

Correct AnswerA. 1,120 kJ

Quick Explanation

An energy yield ratio of 14:3 means energy delivered : energy invested = 14 : 3. For 240 kJ invested, lifetime energy yield is 240×14/3 = 1120 kJ.

Formula / Key Relation

E_yield / E_build = 14/3

E_yield = 240 × 14/3

= 1120 kJ

Detailed Explanation

Concept & Reasoning

Energy yield ratio compares useful lifetime energy output with embodied/build energy. Treat the ratio as a direct proportion. The result should be greater than the construction energy because the numerator 14 exceeds denominator 3.

How to Solve It in the Exam

Ratio output:input → multiply build energy by 14/3.

Important Exam Point

Do a magnitude check: yield must exceed 240 kJ.

Related Revision Path

This question sits in the revision path Power Plant Engineering → Renewable Energy → Energy Payback .

Quick Trick

Ratio output:input → multiply build energy by 14/3.

Common Mistake

Inverting 14:3 and obtaining a value below the energy invested.

Exam Tip

Do a magnitude check: yield must exceed 240 kJ.

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Exam Path

Knowledge Path

Study concept · Energy Yield Ratio →Practice concept Practice topic

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