Electrical resistance of brick

[AngloScot]

Hey. I have to design a laboratory experiment to investigate how the resistance of a house brick varies with temperature in the range of 20 degrees C and 800 degrees C. I know that resistance of a brick is very high so what fsd of voltmeter ammeter etc should i use?

Also, i need a reference in my write up to show where i got the info from ie resistance of a brick, could someone please help me out because i cant find anything on the net.

If anybody else is doing this exam and could point me in the right direction it would be much appreciated.

 thanks, gray

[Missg]

Use a thermo couple and ignore thunder whatever

[liquidoxygen]

Hey, You can use bunsen burners as they can achieve up to 2000 degree temperatures, and as far as regulated heating is concerned, have you considered heating passed 800 and then measuring resistance while it cools. This helps to regulate the temperature and gives you something to mention in the evaluation. I think this is the best you can achieve with standard lab equipment.

[liquidoxygen]

Forgot to mention, the highest voltage you are allowed to suggest using is 5000V as this is the national maximum to be used by students. Lucky We only have to Plan!!

[ob1]

quote: liquidoxygen: "gives you something to mention in the evaluation"

it's just the planning section ********

[AB Editor]

Deleted duplicate answers:

tomd
Wed 06/04/05  It will increase with temperature, as for any material. Resistivity to what? I could assume you mean electrical resistance, in which case it's far too high to be of any use as a conductor or even a semiconductor.
 

   
tomd
Wed 06/04/05  I've read your other posts (here an on some physics forum) and I think a major problem is you intened to measure the resistance for the whole brick, which is going to be huge.

If you took a 5mm slice from a 250mm brick and measured the resistance though that sample (rather than the whole brick) the resistance would be reduced by a factor of 50, hence also the voltage you need to use to gain a measureable current though the thing.

The reduced mass would also make it a lot easier to heat and maintain even temperature throughout.

Thunderchild
Sat 09/04/05  quite true i posted on your previous post on bricks and i am afraid that unless u r more specific we won't get very far. is it still to 800 �C that u have to heat it ?
 

[liquidoxygen]

Sorry, my mistake! but it is still teh only way to really achieve the exercise. If its cooling then its as close to uniform as you can achive in the standard lab, and the bunsens is the only way to go. my problem is the contacts! And mine is due tommorow!!!!!!!!!!!!! Good luck everyone

[dapoka2002]

i am also diong the same course work but i will like to know how to heat the brick too 800 degrees .

[jb748]

well if u look up the data, copper doesnt melt till 1048 C, or sumthin high like that so it should be fine for this experiment. I think the big problem is passing the current over a large enough area to get a good reading, i.e. cover as much surface area at both ends of the brick.

[Thunderchild]

i recomend no more than 1000 volts as that is already very high and u MUST bear in mind that the higher the voltage the more insulation needed like 2mm per 1000 volts and it is advisable to keep the wires at least 1 cm apart. also the maximun voltage of components is a serious issue if this has to be done practically (no i havn't worked out yet if this has to be just desighned or built as well) as 1000 is the general limit so i advise like 500-800 volts.

for uniform heating u could put the brick on a steel plate and heat the plate. the meatal will help to redistribute the heat more evenly but must be removed for the measuring

[obiwankenobi]

you guys suck! we rule we done it! hahahahahaha

[LegoJedi]

Well i am doing the same damn project, and it is giving me a headache. i think all of the things said so far is mostly right, but i must agree when it was said that this project a a bit stupid.  i have to hand my plan in today, but relise that in order to make the thing work, you will have to havce a micro ammeter, and you will have to use in the region of 800 volts, and a very good voltmeter.

i am, at the moment, fed up of this thing, and hope you lot do well, but i am praying that the pratical based on this is a little easier. 

[dinger1990]

I'm also investigating this but without the temperature aspect. I was wondering if anyone knew the best way to connect the brick into the circuit?? I'm not sure but to help others out does anyone know the resistivity of a brick as then you could use the formula concerning the cross sectional area of the brick? not sure if that formula fits your criteria though