A body initially absorbs and emits 80 W. The absorbed power is then increased by 25% and held constant. Over the next 30 s, its average emitted power is 90 W. No other energy transfers occur.
What is the change in internal energy during these 30 s?
a decrease of 300 J300\,\mathrm{J}300J
an increase of 600 J600\,\mathrm{J}600J
a decrease of 600 J600\,\mathrm{J}600J
an increase of 300 J300\,\mathrm{J}300J
96 exam-style questions on Edexcel GCSE Physics 5.3 Black body radiation, covering 5.3.1 Emission of radiation and temperature, 5.3.2 Radiation balance and constant temperature, and 5.3.3 The temperature of the Earth. Each one has a worked solution and a mark scheme showing where the marks go.