How Do Photoelectric Cells Capture Color and Light Intensity?

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Discussion Overview

The discussion revolves around the functioning of photoelectric cells in capturing color and light intensity. Participants explore the mechanisms of electron excitation, the measurement of light frequency, and the determination of light intensity using photoelectric cells, as well as their application in digital camera sensors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question why electrons do not simply move to a higher energy level instead of being ejected from the atom when hit by a photon.
  • One explanation suggests that the energy gained by the electron is too high, leaving no available energy states for it to remain bound to the nucleus.
  • Participants propose using a spectrograph with multiple photoelectric cells or employing filters to measure light intensity, noting that a photocell alone cannot measure the frequency of incoming light.
  • To find the intensity of light, measuring the voltage and current from the photoelectric cell is suggested as a method to determine power.
  • A participant inquires about the structure of digital camera sensors, specifically whether they consist of RGB filtered photocells for each pixel.
  • Another participant confirms that camera sensors typically use CCD or CMOS technology with a Bayer filter to capture color images.

Areas of Agreement / Disagreement

Participants generally agree on the mechanisms of electron ejection and the use of filters in measuring light characteristics, but there is no consensus on the best method to measure light frequency using photoelectric cells.

Contextual Notes

Some assumptions about the energy states of electrons and the specific configurations of photoelectric cells and camera sensors are not fully explored, leaving room for further discussion.

Who May Find This Useful

This discussion may be of interest to individuals studying optics, photonics, or those curious about the technology behind digital imaging and photoelectric devices.

Manasan3010
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In this article, writer says that when atom is hit by photon it gets excited and expelled out of atom and this can be used to form images.
My questions are:
  1. Why didn't the electrons get to a higher energy level, instead of getting knocked out?
  2. How do we find the color(frequency of wave) using photoelectric cell?
  3. How do we find the intensity of the light using photoelectric cell?
 
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Manasan3010 said:
Why didn't the electrons get to a higher energy level, instead of getting knocked out?

The energy it gained was too high. There were no available energy states for that amount of energy that still allowed the electron to be bound to its nucleus. Basically, the 'kick' was too hard and ejected the electron from the atom.

Manasan3010 said:
How do we find the color(frequency of wave) using photoelectric cell?

I suppose you could use a spectrograph that has a number of photoelectric cells as its sensor. Or filter the light using various filters and measure the intensity of the light on the cell for each one. There's really no way to measure the frequency of the incoming light using just a photocell.

Manasan3010 said:
How do we find the intensity of the light using photoelectric cell?

Measure the voltage and current provided by the cell to find the power, which allows you to find the intensity of the light falling onto the sensor.
 
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Drakkith said:
The energy it gained was too high. There were no available energy states for that amount of energy that still allowed the electron to be bound to its nucleus. Basically, the 'kick' was too hard and ejected the electron from the atom.
I suppose you could use a spectrograph that has a number of photoelectric cells as its sensor. Or filter the light using various filters and measure the intensity of the light on the cell for each one. There's really no way to measure the frequency of the incoming light using just a photocell.
Measure the voltage and current provided by the cell to find the power, which allows you to find the intensity of the light falling onto the sensor.

Thank You for the simple explanation, So does the digital camera's sensor consists of RGB filtered photocell for each pixel
 
Manasan3010 said:
So does the digital camera's sensor consists of RGB filtered photocell for each pixel

Pretty much. Camera sensors are typically CCD or CMOS sensors with a bayer filter installed. A bayer filter is just a series of alternating red, green, and blue filters installed on top of the pixels. The camera's software knows the pattern of the filters and generates a color image by combining adjacent pixels.
 

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