Photons, the photoelectric effect, E = m·c² and half-life
Slide the number of half-lives — each step halves what's left of the 800 g sample.
✨ Light arrives in packets — photons
Each photon carries E = h·f. Blue light (high f) packs more energy than red (low f).
N = 800 ÷ 2¹ = 800 × ½
Remaining = 400 g
Fraction left: ½
Each half-life removes HALF of what was there — never a fixed amount.