Where Your Phone Battery Actually Goes (Physics Level 8)

Here's the deal: we're going to follow every single joule out of a dying phone and find out where it actually goes. Then we'll hit a weirder question: if all that energy is sitting in your room right now, why isn't your room roasting?

Your phone didn't destroy its energy. It smeared it across the whole room, adding loads of joules but almost no degrees, until everything reached the same temperature. 'Dead' doesn't mean empty. It means spread out. Now the listener can say that energy (J) is conserved and transferred between stores, that wasted energy is dissipated to the surroundings, and that temperature (°C) is not thermal energy (J). Thermal energy depends on mass, material and temperature: about 4200 J to warm 1 kg of water by 1 °C.

Sources:

• https://cdn.bad.org.uk/uploads/2022/01/29200046/James-Prescott-Joule.pdf
• https://collection.sciencemuseumgroup.org.uk/objects/co2526/mechanical-equivalent-of-heat-apparatus
• https://www.aps.org/apsnews/2009/12/joule-abstract-converting-mechanical-heat
• https://mcq.sg/blog/heat-vs-temperature
• https://physicstribune.com/thermodynamics/heat/
• https://homework.study.com/explanation/what-has-more-heat-a-cup-of-boiling-water-or-a-bathtub-full-of-20-o-c-water-why.html
• https://www.gauthmath.com/solution/1812633355147333/2-A-cup-of-water-and-a-bathtub-full-of-water-are-at-the-same-temperature-but-hav

Source: Episode 14 - Physics Level 8, Energy and Temperature (14/17)
Style: Exam prep
Length: 1166 words, 6 min target
Generated: 2026-10-25