How to determine the concentration and sign of the charge carriers in copper I need to design a procedure for an experiment to determine the concentration and sign of the charge carriers in copper. I'm given:


*

*A slab of copper 2.0 mm thick, 1.5 cm wide, and 4 cm long

*One very sensitive digital multimeter

*One standard digital multimeter

*A DC power supply (any voltage)

*Typical clips (banana clips, etc.)

*Super glue

*Scotch tape


The main confusion that I'm having is how i would be able to create a magnetic field and measure the magnitude. If i did this then to determine the concentration we could use the formula n = -$J_x$$B_y$$/$$q$$E_x$ where $J_x$ is the current density, $B_y$ is the magnetic field, $E_x$ is the electric field, and $q$ is the charge of an electron. Then to determine the sign of the charge carriers we would just look at the Hall coefficient. Which it should be negative, since the mobile charges in metals are negatively charged (electrons).
Thanks in advance for any help, I wanna stress the fact that I don't want to just be given the answer if possible. Just a step in the right direction. Thanks again! :) 
 A: Maybe you don't have to create the magnetic field, you may just use the Earth's magnetic field. As you don't want a complete answer, maybe I should not add anything.
Another possibility: you can use a magnetic field of a current.
A: I would use a solenoid. Place two coils above and below the sheet. Something like:

You can simply calculate the field strength from the coil radius, number of turns and the current, and you'll get a pretty accurate result. However you need to multiply the calculated field strength by the magnetic permeability of copper.
A: You're not given a long wire and an additional current source to create a magnetic field, nor a permanent magnet, so you'll have to stick with the Earth magnetic field. You'll have to figure out where the North is and whether the North counts as a magnetic North pole or South pole. That's enough to get the sign of the charge carriers and a ballpark estimate of the concentration. For anything accurate, you'll need to know the exact magnitude and direction of the Earth field with a good accuracy.
If you do have a wire: build a Helmholtz coil, to create a uniform field.
As for the additional current source: you could put the coil in series with the copper plate.
