A heliumneon laser emits light at 6328 nm If the laser emits

A helium-neon laser emits light at 632.8 nm. If the laser emits 1.99 its power output in mW? 1017 photons/second, what is A) 40.6 mW B) 62.5 mW C) 31.3 mW D) 50.0 mW

Solution

Energy

E=hc/lambda =(6.626*10^-34)(3*10⁸)/(632.8*10^-9)

E=3.14*10^-19 J

Power Output

P=(3.14*10^-19)(1.99*10¹⁷)

P=0.0625 W =62.5 mW