solar/photo cells (2 Viewers)

[ashtor]

the sylabus asks to summarise the use of the photoelectric effect in:
- solar cells
- photocells,
whats the difference between the two, dont they so the same thing using sunlight??

 

[Rorix]

no.

photocells are things such as light sensors for photography, intruder alarms, those annoying door trip chime things etc.

 

[:: ck ::]

different things

photocell has like a cathode coated with photosensitive material and an anode...

when the light falls on the cathode it emits photoeletrons in the dir of the anode so thus theres a current produced.... proportional to the light intensitty falling on it

solar cell is a bit more complicated.. basically theres an "n type" junction and a "p type" junction separated by a p-n type junction

we kno that the n type has free electron and thus leaves the n type junction to go to the p type junction [that has holes] and thius leaves the n type junction with holes [roles reversed] and thus sets up an electric field

wots the point of it? well it restricts the flow of electrons to only go from n type to the p type

anyways wen light falls on the n type layer there are these electron hole pairs formed and due to the photo electric effect which frees theelectrons from their bonds amd flows from n type junction to the p type junction and out to ur external circuit

that is off the top of my memory tho..

 

[ashtor]

but in our texbook, Jacaranda physics 2 it says that most modern photoconductive cells are made of semiconductor mmaterial. Duznt that make em solar cells?

 

[:: ck ::]

solar cells have a specific build...
as long as theres a n type and p type and "p-n type" junction and is conected to an exteernal circuit... u call it a solar cel

 

[kimmeh]

dont solar cells have semiconducting propeties/build to it ?

 

[Xayma]

Basically solar cells generate electricity from sunlight.

Photo cells, rely on the fact that resistance changes when light falls on a material.

Ie Breathalysers send a beam of light through the bag into which you just blew, condensing alcohol scatters this light. A resistor is on the other side by measuring the change in resistance, the amount of alcohol can be determined.

 

[Talame]

Ok, I have an assignment to do on photocells and solar cells... is the basic difference between them their use?