Question

A ruby laser produces radiation of wavelength 633 nm in pulses with a duration of 1.00 × 10-9 s. (a) If the laser produces 0.376 J of energy per pulse, how many photons are produced in each pulse? (b) Calculate the power (in watts) delivered by the laser per pulse (1W = 1 J/s).

Answer 1

(a) Energy of each photon , e = hc/wavelength

= 6.63 × 10^-34 Js × 3 × 10^8 m/s/(633 × 10^-9 m)

= 3.14 × 10^-19 J

energy produced per pulse , E = 0.376J

so, number of photons are produced in each pulse = E/e = 0.376/3.14 × 10^-19

= 1.2 × 10^18

(b) power = energy/time

= E/t

= 0.376J/10^-9s

= 0.376 × 10^9 J/s

= 3.76 × 10^8 watt

hence, power delivered by the laser per pulse is 3.76 × 10^8 watt

Answer 2

this is most correct ans