Unknown field and charge carriers' density

[Ikabot]

Hi, I have a problem which I can't resolve. I would like some hints which could help me to resolve it.

A Hall-effect probe operates with a 120-mA current. When the probe is placed in a uniform magnetic field of magnitude 0.080 T, it produces a Hall voltage of 0.700 microV.

a) When it is measuring an unknown magnetic field, the Hall volage is 0.330 microV. What is the magnitude of the unknown field?

b) The thickness of the probe in the direction of B is 2.00 mm. Find the density of the charge carriers, each of which has charge of magnitude e (electron).

Thanks

[Enthalpy]

What have you already tried to resolve it? Because, well, I don't need to learn it any more... [unless it changed meanwhile, of course]

 

Do you know some linearity in the equation of the Hall voltage?

 

When you compute a Hall voltage from the current, carrier density, and dimensions: maybe you have all you need?