physics p & d

Shordaay

i have to plan and design an experiment based on this outline: " excellent thermal conductors are also excellent electrical conductors"

could i get any ideas please?

marcusl

Welcome to PF! It is not the policy here to do students' homework for them, but we can certainly help you when you get stuck. Please start your research, and come back with a post of what you've learned and how you think you might do this experiment. We can reply with comments and suggestions.

nasu

You could show that the statement is not true, in general, by using diamond as an example : excellent thermal conductor (better than copper) and very, very poor electrical conductor (or rather very good insulator).

256bits

I guess salted water would fall under excellent electrical conductor but a so-so thermal conductor.

Bob S

Another is beryllium oxide. See http://en.wikipedia.org/wiki/Beryllium_oxide

nasu

Thank you for the extra example. I did not know about this one.

nasu

It's rather so-so in both respects, if you compare with a metal.

marcusl

Bob, beryllium copper is classified as a hazardous material. Not a good choice for a science project.

Bob S

I attach a Material Safety Data Sheet for beryllium-copper (see http://www.csunitec.com/technical/MS...ium%202008.pdf).

Environmental In solid form, beryllium-copper alloys are not detrimental to the
environment.
Waste treatment Scrap must not be melted or treated in such a way as to release
airborne dust or fog. Scrap material must only be melted in special
furnaces. Scrap material can be handed in at approved disposal sites.
Contact the local authorities in case of doubt.
Transport Transportation of the material in solid form(i.e. in original or scrap
form) is harmless. No EU safety warning is required

Beryllium-copper (up to ~ 3% Be) is a hard springy alloy of copper. We used to have a set of beryllium-copper tools- screwdrivers, pliers, crescent wrenches, for use around big magnets (cyclotrons) and liquid hydrogen targets, because Be-Cu tools are both non magnetic and non sparking. Do not sand or machine beryllium copper, which will produce toxic dust.

Beryllium oxide (http://www.americanberyllia.com/lit/...Oxide_MSDS.pdf), used as a thermally conducting insulator, is harmful, and should not be handled with bare hands. Also true for bare metal, used for thermalizing neutrons and slowing down charged particles with minimum multiple scattering.

flatmaster

You could also talk about the mechanism for conduction. Liquids and gasses can conduct heat via convection; The liquid or gas is actually moving to carry the heat. You can't conduct electricity via convection.

sophiecentaur

AFAIK, Berillium is a dangerous substance to Machine (i.e. if you inhale the dust). You can find it all over the place in high power RF equipment.

Bob S

Look up the physics law relating the ratio of the electronic contribution to the thermal conductivity (κ) and the electrical conductivity (σ).