Scientific reading
Conduct a safe desk-based audit
Choose a fictional device from the supplied case-study dataset. Record total input energy, intended output, thermal pathway and another pathway, all across the same interval. The audit is a mathematical representation, not an appliance efficiency claim. It requires no powered equipment, moving components, thermometers, or exposure to hot surfaces.
Check every conversion and unit
If 800 J comes in and output categories are 480 J useful, 200 J thermal, and 120 J other, their sum is 800 J. Each fraction is its energy divided by 800 J. Useful efficiency is 480/800=60%, not 480%. If you convert to mean powers during a 10 s interval, divide ALL energy categories by 10 s to get watts.
Why design categories matter
The adjective 'useful' has no meaning until the design brief states what a device is meant to do. A device intended to produce heat may classify heat as useful; a motion device often considers unwanted heat a non-useful pathway. Neither category is inherently good or bad independent of context.
Document provenance and uncertainty
These entries are generated from chosen percentages and algebra, not laboratory instruments. Real measurements have resolution, calibration, repeatability and uncertainty. Students can propose an instrument-and-safety plan hypothetically, but the required submission uses the synthetic dataset and explicitly identifies its limitations.