# What sort of experiments can be doen with Graphite ?

1. Jan 30, 2013

### th3whit3fang

What sort of experiments can be doen with Graphite ??

I need experiments that can be done for the research of graphite.. GOt any ideas??

2. Jan 31, 2013

### Philip Wood

Re: What sort of experiments can be doen with Graphite ??

Variation of resistance with temperature.

Carbon microphone.

Different resistances across different pairs of opposite faces in a graphite cube. [I've never tried this, and it might be difficult to do, owing to problems making contact in a standard and reproducible way with the faces. Area of contact (metal to graphite) and pressure applied would need to be the same.]

3. Jan 31, 2013

### Bobbywhy

Re: What sort of experiments can be doen with Graphite ??

th3whit3fang, Welcome to Physics Forums!

http://en.wikipedia.org/wiki/Graphite

Check the sections "Occurrence, Properties, Uses". Don’ t forget these final sections, they can lead to far more information and ideas for your project:

"References"

Cheers,
Bobbywhy

4. Feb 3, 2013

### th3whit3fang

Re: What sort of experiments can be doen with Graphite ??

Can you explain how it could be done with graphite.. i searched for it and i got an experiment but it isn't so clear what was being done in the video..

Last edited by a moderator: Jan 15, 2014
5. Feb 3, 2013

### Philip Wood

Re: What sort of experiments can be doen with Graphite ??

One way to make a carbon microphone is to rest a piece of pencil 'lead' (that is graphite + a binding material) a few centimetres long on the edges of two razor blades. The set-up is $\pi$ shaped, with the razor blades forming the uprights, and the pencil 'lead' forming the bridge across the top. The 'terminals' of the microphone are the razor blades.

Connect the microphone in series with a battery (6 V, perhaps) and a resistor (100 $\Omega$, perhaps. Connect the y-amplifier input terminals of an oscilloscope across the resistor. Speak loudly near the pencil lead and you should see a corresponding trace on the oscilloscope, when you've adjusted the time-base and the y-gain.

It works - if it does work! - by the pressure variations in air due to the sound waves pushing the 'lead' more and less firmly on to the blades, changing the contact resistance between blades and lead. The series resistor completes a potential divider circuit.

Until quite recently carbon microphones (using carbon granules) were the standard microphone in telephone handsets. The quality of reproduction was never good.

Last edited: Feb 3, 2013
6. Feb 4, 2013

### th3whit3fang

Re: What sort of experiments can be doen with Graphite ??

Thanks man !!!

7. Feb 4, 2013

### Philip Wood

Re: What sort of experiments can be doen with Graphite ??

Please post if you try it.

8. Feb 5, 2013

### DrZoidberg

Re: What sort of experiments can be doen with Graphite ??