Final answer:
The Hall effect can be used to determine free charge density in a conductor by measuring the Hall voltage and the applied magnetic field, allowing for the calculation of charge carriers per unit volume.
Step-by-step explanation:
To discuss how the Hall effect could be used to obtain information on free charge density in a conductor, it is important to understand the relationship between drift velocity and current. The Hall effect refers to the production of a voltage (Hall emf) across a current-carrying conductor placed in a magnetic field perpendicular to the charge carrier's movement. By measuring the Hall voltage and knowing the magnetic field strength, thickness of the conductor, and current, one can determine the free charge density and drift velocity of the charge carriers. Specifically, this information is used to calculate the number of charge carriers per unit volume, as the Hall voltage is proportional to the applied magnetic field and inversely proportional to the charge carrier density.
The free charge density is inversely related to the Hall coefficient, RH, which is obtained from the Hall voltage. This is because the Hall coefficient is defined as RH = E / (jB), where E is the Hall electric field, j is the current density, and B is the magnetic field. With this, one can deduce that the accurate answer to the question is: By measuring the Hall voltage and the applied magnetic field, the free charge density and drift velocity can be determined.