Question

Could you measure the Earth's magnetic field (magnitude and direction) using the magnetic field sensor? If so, How? If not, why not?

Answer 1

   Measuring the magnetic field of earth with sensor
   In many materials, these moving charges are electrons
   An electric charge in the presence of an electric field experiences a force with a magnitude equal to the product of the electric charge and the electric field.
   A moving electric charge also experiences a force when in a magnetic field (it has to be moving). This force depends on the magnetic field, the charge and the speed.
   The direction of this force is perpendicular to both the magnetic field and the velocity vector of the electric charge.
   If WE have an electric field in some region, that will cause a change in electric potential between two points.

   Resulting a force     F = Eq + B X vq

   Also, if we have an electric field the change in electric potential between two points is delta v = - integral 1,2 E.dr
       now hall sensor
      
   

  
    Surface charge builds up on the side due to the magnetic force on the moving charge carriers.
    This surface electric charge creates an electric field.
    The electric field (due to the side surface charges – there is also an electric field that causes the current) exerts a force on the moving charges.
    The side surfaces charges will keep building up until there is an sideways electric force that cancels the magnetic force and the electrons again move in the direction of the wire.
    This electric field also means that there is a change in electric potential across the material (which we can measure).

   Eq = Bqv
   B = E/ v
and change in potential is mesuring as

                                                             
                      
   This is the magnetic field of the earth.