Final answer:
The magnetic flux density B in free space is correctly represented by the formula B = μ0H, where μ0 is the permeability of free space and H is the magnetic field strength.
Step-by-step explanation:
The question pertains to the relationship between magnetic flux density and other magnetic quantities in free space. The correct expression for the magnetic flux density B in free space, in terms of the magnetic field strength H and the permeability of free space μ0, is B = μ0H.
The constant μ0, also known as the "permeability of free space", has a value of approximately 4 × 10-7 Tm/A. The magnetic field strength H is related to factors such as current and geometry of the conductors.
Therefore, the correct answer to the student's question is option d: μ0H.