How does the wavelength of light affect its intensity?

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SUMMARY

The discussion focuses on the relationship between the wavelength of light and its intensity, specifically in the context of a sodium and mercury visible light spectroscopy lab using a photomultiplier tube (PMT). The participant clarified that the energy of a photon can be expressed as hc/λ, and power can be calculated using the formula (hc/λ) * N/T, where N is the photon count and T is the counting time. The participant concluded that intensity (I) can be directly related to power (P) without the need for a cosine correction due to the geometry of the photon emission.

PREREQUISITES
  • Understanding of electromagnetic radiation wave equations
  • Familiarity with the concepts of photon energy and intensity
  • Knowledge of spectroscopy techniques and equipment, specifically photomultiplier tubes (PMTs)
  • Basic grasp of the relationship between wavelength and energy (E=hc/λ)
NEXT STEPS
  • Study the derivation of the wave equations for electromagnetic radiation
  • Learn about the principles of spectroscopy and the operation of photomultiplier tubes (PMTs)
  • Explore the relationship between intensity and power in the context of light sources
  • Investigate the implications of the uncertainty principle on photon energy measurements
USEFUL FOR

This discussion is beneficial for physics students, laboratory technicians, and researchers involved in optical spectroscopy, as well as anyone interested in the quantitative analysis of light intensity and wavelength relationships.

Drax
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hey everyone,

Homework Statement



I'm doing a sodium and mercury visible light spectroscopy lab at the moment. By using a PMT, I can detect the intensity of photons emitted as a function of wavelength (controlled parameter). I was wondering if anyone knows how the two relate theoretically.

The index of refraction I'm working with is that of air.

Homework Equations



n=sqrt(eps*mu) of air
U=1/2 eps E^2
U is the energy volume density stored by the Efield wave of the light
and E is not the Efield but somehow related to the amplitude.
P=Uv
I=P/A
E=hv?
possibly more?

The Attempt at a Solution



Well, I don't know too much yet about the wave equations describing electromagnetic radiation, but I do know how the de broglie wavelength relates to energy. The first equation I don't really understand in terms of derivation. Furthermore, I'm not sure if U relates to the complex or real amplitude squared of the E field. I'm very comfortable with the de broglie wavelength implications for photons but I'm not sure finding the Schrödinger energy of the photon will get me any closer to finding the power because of the uncertainty equation for energy and time. I'm lost at this point at how to approach relating Intensity to wavelength

Thanks for the help
 
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Nevermind. I figured it out.

For those who ever come across this,
hc/lamda = energy of photon,
but (hc/lamda)*N/T=Power
where N is the photon count and T is the time you count them for.
since A of the spectroscopy detector is far away from the source relative to its magnitude,
the curvature of the sphere of photons emitted is approximately parallel to A. Thus IA=P without worry of a cos term.
 

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