Investigation on a Light Dependant Resistor

[Bob Spoongfield]

Yer I think that they just want us to think complicated, but actually realize that it is something a lot simpler. I am just going to use current against wavelength and resistance against wavelength and see which one looks more like the one it should

 

[andy262]

i am doing the same palnning exercise and my teacher suggested using a spectrometer but I am not sure how it works can anyone help?

 

[United fan]

does anyone know the accuracy and range of the standard voltmetres and ammetres used in schools? as we need to write this too i think

 

[Justicazza]

i am confused over whether a diffraction grating would work when determining a wavelngth of a specific filter - http://www.physics.smu.edu/~scalise/emmanual/diffraction/lab.html refers to a assumed white light source so if i use the diffraction grating whilst the filter is in place over the source would i still get the spectrum of colors?

its a toss up between going for the inaccurate method of predetermined wavelength filters and diffraction gratings - anyone know of another known method of measuring the wavelength of the light through a filter which can be used as an AS level explanation?

 

[Bob Spoongfield]

i am doing the same palnning exercise and my teacher suggested using a spectrometer but I am not sure how it works can anyone help?

Try the Phillip Harris website and Rapid Electronics... they are both suppliers for schools

 

[RBanana]

All you have to do is separate the light using filters, then place the LDR in each colour of light (make sure it's the same distance from light source etc to keep it a fair test) and then you can find the resistance using a multimeter (but it on the ohm setting).
Find a transfer graph from a LDR manufacturer (resistance against intensity)- this will count for your biblography. Then using this graph, you can use the resistance you found for each colour, and find out intensity.
To find wavelength just use Young's Double Slit interference for each colour.
Lambda= ax/d where a is distance between the slits, x is fringe separation and d is distance from the slits to the screen.
That's basically what I've done, add more detail etc. My teacher was saying how realistically it would be hard to do, but it doesn't matter because we're only doing a plan.
After all, it is only worth like 2% of the whole A level...

 

[fblade]

for (b) my teach said to read it off the filters. And (c) use the Current as the Intensity. I have also found another equation: R = 500/Intensity. Could I measure the Resistance and find the intensity via the equation?

Im not sure on how to answer (d) the range and precision of any instruments that would be used?

Thanks.

 

[MattyB]

If you use a single slit first to get a diffraction patern then the Youngs Double slit interference will work for the lamp as it creates light in single waves from one point

hope this helps!

 

[DKOli]

lol intensity=power/area - hope no1 used that 2day. How about you guys learn physics first before posting.

r=500/i lux kOhm.

keep it simple. The area for that equation is not going to be using a raduis of distance between source to ldr. That would find intensity within sphere NOT IN LDR - to do that u'd need inverse square rules etc etc. Sorry the post is late but i found this forum right before beginning my planning exam.