Question

Lasers are now used in eye surgery. Given the wavelength of a certain laser is 514 nm and the power of the laser is 1.6 W, how many photons are released if the laser is used for 0.058 s during the surgery?

Answer 1

Energy of a photon =hv
h=6.626*10^-34
v=frequency=3*10^8/*(514*10^-9)
E =3.8673*10^-17 Joules
now lase operates for 0.058 seconds
Power=1.6w
Energy released in this time=1.6*0.058
=0.0928 Joules
No. of Photons=Total Energy released/energy of a photon
=0.0928/(3.8673*10^-17)
=0.02399*10^17
no. of photons released =2.399*10^15

Answer 2

Off by a power of ten but none the less the reasoning is right!