[SOLVED] help needed on photocells please.

imogen89

now, i am doing the same planning excersise as einstein was--->and i was wondering, do you think that it would be enough to do the experiment you mentioned earlier where you just attatch a DVM on mA setting to the photocell, or whether it would give more of a valid conclusion to do the thing where you put a resistor and a voltage divider [?] into the circuit and measure the voltage?

imogen89

yea that's what i thought, but it says to plug the circuit into analogue in on the circuit diagram [half way down the page that the other guy gave me a link for]...where is that wire going. or do i not even need to know...

razor12

One thing to watch out for is the example posted on the last page is for a light dependent resistor, a standard LDR will not react to IR as its wavelength is too long, this means the only thing it will do is react to visable light,
You can in theory get LDR's that respond to IR (think they are, Ge:Cu)but you need to use components you can source

welshdragon

Will you please help im confused
Ive been told by my physics tutor to connect the photocell to a battery, and take a reading of the current.
Would this work?

THANX

dolarpounds

could you help me with the apparatud that will be used for this experiment

rich_b62003

Ok heres my take on things.
I am also doing this experiment and whil it seemed a bit strange at first its not so bad. Really just asking berkemen and hootenanny whether what ive done is the right sort of lines. A few people have mentioned batteries. however having done a bit of reading on photocells i thought they generated current themselves, so ive left out a battery. By the way not sure if anybody has acctually clarified this. We dont acctually do the experiment, just plan it. my plan is to have the photocell connected to a fixed resistor with a large resistance, and to measure the voltage acroos that large resistance. From that i could work out the current using simple maths.
think thats right but just a yes or no would help enormously

Hootenanny

Yes, this should work but you may only obtain a limited range of data.

~H

Hootenanny

This would probably work, but it would depend on how sensitive your voltmeter is and it is likely your obtained curve will not be nice . If you want simplicity a better method to use would be to connect your photocell directly to an ammeter and measure the current.

~H

me2

hmmmm i believe im doing the exact same question! im just as stuck, i was under the impresion that you simply hook up a curcit with a powersource, the photocell and reviver thing (is that the diode?) and an ammeter, then alter the distances and ,easure the current.
am i any where near right?