Question

A 193nm-wavelength UV laser for eye surgery emits a 0.500mJ pulse. (a) How many photons does the light pulse contain?

Answer 1

Answer:

The number of photons is 4.8x10^14

Explanation:

The frequency of wave is equal to:

$f=\frac{c}{l}$

where c is the speed of light, l is the wavelength of wave. Replacing values:

$f=\frac{3x10^{8} }{193x10^{9} } =1.5x10^{15} Hz$

The energy of the proton is:

$E=hf$

where h is the Planck´s constant. Replacing

$E=6.626x10^{-34}*1.5x10^{5}=1.03x10^{-18} J$

The number of photons is:

$n=\frac{E1}{E}$

where E1 is the energy of photon. Replacing:

$n=\frac{0.5x10^{-3} }{1.03x10^{-18} }=4.8x10^{14}$

Answer 2

Using the equation E = hc/λ we can find out how much energy a single photon of wavelength 193 nm has. E = Planck Constant * Speed of Light/193 nm