A: Calculating Photon Count from Electrical Energy and Efficiency

  • Thread starter Thread starter wildredhead
  • Start date Start date
  • Tags Tags
    Electric Photo
AI Thread Summary
The discussion focuses on calculating the number of photons emitted by a 60-watt incandescent bulb operating at 2.2% efficiency, specifically for green light at a wavelength of 5500 Å. To determine the photons per second, one must first calculate the energy produced as visible light and then use the formula E=hf to find the energy per photon. The second part of the problem involves calculating how many photons enter the eye when standing 3.5 meters away from the bulb for 0.10 seconds, considering the pupil's diameter. Participants express uncertainty about the equations and approach needed for the calculations. Overall, the thread emphasizes the need for a structured approach to solve both parts of the problem effectively.
wildredhead
Messages
7
Reaction score
0

Homework Statement


In converting electrical energy into light energy, a sixty-watt incandescent light bulb operates at
about 2.2% efficiency. Assuming that all of the light is green light (wavelength approximately
5500 Å), determine the number of photons per second given off by the bulb and B:if you were to look directly at the bulb, the light
from it would travel directly to your eye without reflecting from anything. If you stand 3.5
meters away and look at the bulb for only 0.10 seconds, how many photons will enter your eye?
(assume the pupil of your eye has a diameter of 2.1 mm)


Homework Equations


I don't really know what to use.
I think E= hf


The Attempt at a Solution


First I converted angstroms to wavelength then I found frequency. From frequency and planks constant I found E but then I got nothing . DOn't even know how to touch B.
 
Physics news on Phys.org
For (A), you need to answer two questions first:

1. How many Joules per second are produced in the form of visible light?

2. How many Joules of energy are in one photon? (Use the answer you got from using E=hf)
 
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Photon Arrival Rate, Chapter 1.5 from Computer Graphics by Folly
Replies
15
Views
2K
Calculating the Planck Length
Replies
3
Views
205
Find Photons per second on the eye from a source a distance away
Replies
7
Views
4K
Is the Photoelectric Effect Proof That Light Is a Particle?
Replies
35
Views
3K
Photons per second from lightbulb
Replies
3
Views
2K
Hydrogen Emission Spectrum and Electron Energy Levels
Replies
2
Views
2K
Number of emitted photons per second
Replies
2
Views
3K
B Using Interference Principles to Increase the Efficiency of Solar Panels
Replies
0
Views
1K
Efficiency of a Light Bulb: Calculating Energy Transfer
Replies
2
Views
2K
I Energy Flow From Battery to the Light Bulb
Replies
16
Views
4K

Hot Threads

Recent Insights

Back
Top