A narrow beam of light has entered a large thin glass plate. Each refraction is accompanied by reflection of one third of the beam's energy. What percentage of the light energy is transmitted through the plate?

Question

G1 Physics · Accepted Answer

Each surface has reflection fraction R=1/3 and transmission T=2/3. Total transmitted fraction is T²[1+R²+R⁴+…]=(4/9)/(1-1/9)=1/2=50%. Answer: 50.