# Journal Prompt: Where Does the "Useful" Energy Go?

Every energy conversion device you rely on, from a car engine to a light bulb, loses some energy as unwanted heat.

**Prompt: Choose one technological device you use regularly (for example, a car, a refrigerator, or a furnace). Describe the energy conversions it performs, then explain why it cannot convert 100% of its input energy into useful output, tied to [Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43862).**

### Where to start:
- What form of energy enters your device, and what form does it produce as useful output?
- Where does the "lost" energy go, and in what form does it usually leave the system?
- Why do the first and second laws of thermodynamics make a perfectly efficient device impossible ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43862))?
- How might an engineer measure or improve this device's efficiency?

### Stretch:
Research the approximate efficiency rating of your chosen device and compare it to a different technology that performs a similar function (for example, an incandescent bulb versus an LED). Explain which design choices account for the difference in efficiency.

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*AILI prompt · language en · model claude-sonnet-5 · generated 2026-09-17 · id c1a29d68-0bfa-4df3-8443-7098cbbbc172*

### Sources

- node:n1: Sciences › Science (10) › Science 10 › Unit B: Energy Flow in Technological Systems › Outcomes for Science, Technology & Society (STS) & Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43861)
- node:n2: Sciences › Science (10) › Science 10 › Unit B: Energy Flow in Technological Systems › Outcomes for Science, Technology & Society (STS) & Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43860)
- node:n3: Sciences › Science (10) › Science 10 › Unit B: Energy Flow in Technological Systems › Outcomes for Science, Technology & Society (STS) & Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43862)
- node:n4: Sciences › Science (10) › Science 10 › Unit B: Energy Flow in Technological Systems › Outcomes for Science, Technology & Society (STS) & Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43860)
- node:n5: Sciences › Science (10) › Science 10 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43858)
- node:n6: Sciences › Science (10) › Science 10 › Unit B: Energy Flow in Technological Systems › Outcomes for Science, Technology & Society (STS) & Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/43861)
- resource:r1: Resources › type#studentsupport, type#teachersupport › SCN1270 (https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/YQCD0P1WtkevzZOoU5Bg1Q)