Photoelectric Cells: What Are They and Why Evacuated?

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In summary, photoelectric cells work by freeing electrons when light of a certain frequency hits a metal, which then travel towards the positive cathode. The reason they are evacuated is to prevent possible collisions with oxygen and other electronegative gases that could ionize them, resulting in a smaller or no reading on the current meter.
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bael
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I was wondering why photoelectric cells are evacuated
 
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Think how they work.
 
  • #3
Borek said:
Think how they work.

light of a certain frequency hits a metal and frees some electrons, which then travel toward the positive cathode.
 
  • #4
So far so good. Now think about the "travel towards the cathode part".
 
  • #5
Borek said:
So far so good. Now think about the "travel towards the cathode part".

is it because the electrons could possibly collide with the oxygen and other electronegative gases, ionizing them and thus giving a smaller reading on the current meter?
 
  • #6
bael said:
is it because the electrons could possibly collide with the oxygen and other electronegative gases, ionizing them and thus giving a smaller reading on the current meter?

More precisely "giving no reading".
 

FAQ: Photoelectric Cells: What Are They and Why Evacuated?

What is a photoelectric cell?

A photoelectric cell, also known as a photocell, is an electronic device that converts light energy into electrical energy. It consists of a thin metal plate or semiconductor material that is exposed to light and connected to a circuit.

How does a photoelectric cell work?

When light hits the metal plate or semiconductor material, it causes electrons to be emitted from the surface. These electrons are then collected by a positively charged electrode, creating a flow of electrical current. The intensity of the light affects the number of electrons emitted, thus controlling the amount of current produced.

Why are photoelectric cells often placed in evacuated tubes?

Photoelectric cells are often placed in evacuated tubes to reduce the interference of air molecules. In a vacuum, there are fewer air molecules to scatter or absorb the light, resulting in a more accurate measurement of the light intensity.

What are the applications of photoelectric cells?

Photoelectric cells have a wide range of applications, including light meters, solar panels, and even barcode scanners. They are also used in automatic doors, burglar alarms, and traffic sensors.

What are the advantages of using photoelectric cells?

One of the main advantages of photoelectric cells is their ability to convert light energy into electrical energy with high efficiency. They are also highly durable and have a long lifespan, making them a cost-effective option. Additionally, they do not require any external power source, making them a sustainable and environmentally friendly choice.

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