Number of photons emitted from a light bulb entering the eye

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SUMMARY

The discussion focuses on calculating the number of photons emitted from a 100W light bulb with a wavelength of 6000 x 10^-10 m that enter the eye from a distance of 1 meter. The energy of each photon is determined using the equation E = hc/lambda. The proportion of light entering the eye is calculated by comparing the area of the pupil to the surface area of a sphere, with the pupil's area derived from the formula for a circle, A = πr². The user successfully identifies the necessary equations and relationships to solve the problem.

PREREQUISITES
  • Understanding of the equation E = hc/lambda for photon energy calculation
  • Knowledge of geometric formulas, specifically area of a circle (A = πr²)
  • Familiarity with the concept of light intensity and its distribution in space
  • Basic principles of optics related to human vision and pupil size
NEXT STEPS
  • Calculate the total energy emitted by a 100W bulb per second
  • Explore the concept of luminous flux and its relation to photon emission
  • Learn about the effects of distance on light intensity and photon distribution
  • Investigate the role of pupil size in light perception and its physiological implications
USEFUL FOR

Students studying physics, particularly in optics and photonics, as well as educators looking for practical examples of light behavior and calculations related to human vision.

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Homework Statement



A 100W bulb emits light of a single wavelength 6000*10^-10 m. If light spreads out uniformly in space, how many photons enter your eye per second if you are at a distance 1m from the bulb and the pupil diameter is about 1mm?

Homework Equations



E = hc/lambda

The Attempt at a Solution



I found the energy of each photon using E =hc/lambda and i know i have to divide the proportion of light entering the eye by this to find the number of photons entering the eye. I also know that the proportion of light entering the eye is area of pupil/ area of sphere. the area of sphere is 4*pi*r^2 = 4*pi*1 but what is the area of the pupil?
 
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The pupil is a circle. What's the formula for area of a circle?
 
pi*r^2
i assumed it would've been harder to find.
thanks so much!
 

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