Number of photons emitted from a laser

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SUMMARY

The discussion centers on calculating the number of photons emitted per second by a 35mW laser producing 526nm green light. The correct calculation involves using the equation E=hf to determine the energy of a single photon and then dividing the total power output of the laser by this energy. The final answer is determined to be approximately 1.9×1017 photons emitted per second. The user initially struggled with the concepts but received assistance that clarified the necessary calculations.

PREREQUISITES
  • Understanding of the equation E=hf for photon energy calculation
  • Knowledge of wavelength and frequency relationships
  • Familiarity with the concept of power in watts
  • Basic grasp of the photoelectric effect and photon properties
NEXT STEPS
  • Study the relationship between wavelength and frequency in electromagnetic waves
  • Learn how to apply the equation E=hf in different contexts
  • Explore the photoelectric effect and its implications in quantum physics
  • Investigate the properties of lasers, including power output and photon emission
USEFUL FOR

Physics students, educators, and anyone interested in understanding laser technology and photon calculations will benefit from this discussion.

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Homework Statement


A 35mW laser produces 526nm green light.
What is the number of photons it emits each second?
1.9×1017
1.9×1018
1.0×1017
9.3×1016


Homework Equations





The Attempt at a Solution


I've been playing with E=hf and lambda = h/p ----- no success!
The textbook I am using doesn't have much on photons/photoelectric effect - nothing that helps me with this question at least. the "photon wavelength-momentum relation" is I think the most relevant to this question?? The textbook doesn't actually say what p is so I assumed number of photons but that's wrong since it doesn't work.

anyway need some help please.
 
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Calculate the energy of one photon. You need to get the frequency from the wavelength.

ehild
 
thanks ehild - solved the problem
 

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