Question

a ruby laser produces radiation of wavelength 632 nm in pulses with a duration of 1.00×10^-9 s. if the laser produces 0.575 j of energy per pulse, how many photons are produced in each pulse? round your answer to 3 significant digits.

Explanation:

Step1: Calculate the energy of a single photon

The energy of a photon is given by the formula \(E = hc/\lambda\), where \(h = 6.626\times10^{-34}\space J\cdot s\) (Planck's constant), \(c = 3\times10^{8}\space m/s\) (speed of light), and \(\lambda=632\times10^{-9}\space m\) (wavelength).

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Step2: Calculate the number of photons

If the total energy per pulse \(E_{total}=0.575\space J\), and the energy of a single photon \(E = 3.145\times10^{-19}\space J\), then the number of photons \(n=\frac{E_{total}}{E}\)

$$ n=\frac{0.575}{3.145\times 10^{-19}}=\frac{0.575\times10^{19}}{3.145}\approx1.83\times 10^{18} $$

Answer:

\(1.83\times 10^{18}\)