How Do You Calculate Photon Flux on a Surface?

In summary, the problem involves finding the photon flux that hits a 2 sq. meter surface with a power of 10W/m^2 and a wavelength of 600nm. The emitted flux equation (P/hv) is connected to the flux hitting the surface, and the intensity of light on the surface is already given in the question. Therefore, the solution involves finding the number of photons reaching the surface each second using Planck's constant relation E=hc/l.
  • #1
vagab0nd
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Homework Statement


An area of 2 sq. meter is lit with power 10W/m^2 with light on wave length equal to 600nm.
What is the photon flux that HIT the 2 sq. meter surface.


Homework Equations


E=hv - plank const and frequency (c/lambda)
Photon flux of EMITTED source is flux=N/t=P/hv


The Attempt at a Solution


It seems, that somehow the emitted flux P/hv has to be connected with flux that hit the surface...
 
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  • #2
It seems that the question is stated in terms of the intensity of light on the surface (a constant 10W/(m^2) - note that this is INTENSITY, not power). In this case there is no need to calculate the intensity of light falling on the surface from the power of the source - it is given in the question. In that case, it is simply a matter of finding the number of photons in the 20 Joules that reach the surface each second from the Planck's constant relation given, E=hc/l.
 
  • #3


Yes, you are correct. The photon flux on the surface can be calculated using the formula for photon flux of an emitted source, as you mentioned. However, it is important to note that photon flux is a measure of the number of photons hitting a given area per unit time. In this case, the power of the light source (10W/m^2) and the wavelength of the light (600nm) can be used to calculate the photon flux on the surface using the formula: Flux = P/hv = (10W/m^2)*(1 photon/4.96x10^-19 J)*(c/lambda) = 1.2x10^21 photons/m^2s. This means that for every second, 1.2x10^21 photons will hit the 2 sq. meter surface.
 

1. What is photon flux on surface?

Photon flux on surface refers to the number of photons (particles of light) that are incident on a specific surface per unit time. It is a measure of the intensity of light that is hitting the surface.

2. How is photon flux on surface measured?

Photon flux on surface is typically measured using a device called a photometer, which detects and measures the amount of light hitting a surface. The unit of measurement for photon flux on surface is photons per second per square meter (photons/s/m2).

3. What factors affect photon flux on surface?

The amount of photon flux on surface is affected by factors such as the distance between the light source and the surface, the intensity and wavelength of the light, and any obstructions or reflections that may alter the amount of light reaching the surface.

4. Why is photon flux on surface important?

Photon flux on surface is important in various fields of science, such as optics, astronomy, and biology. It helps us understand the amount of light energy that is reaching a surface, which is crucial in determining the behavior of light and its interactions with matter.

5. How does photon flux on surface relate to photosynthesis?

In photosynthesis, photon flux on surface is a key factor in determining the rate of photosynthesis. Plants use the energy from photons to convert carbon dioxide and water into glucose and oxygen. The higher the photon flux on surface, the more energy is available for photosynthesis to occur.

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