Question

In the comparison between Coulomb's law (electric field) and the Biot–Savart law (magnetic field), the source of the field is:

Options

• a scalar in both laws

• a vector (electric charge) in Coulomb's law; a scalar (current element) in the Biot–Savart law

• a scalar (electric charge) in Coulomb's law; a vector (current element I dl) in the Biot–Savart law

• a vector in both laws

Answer 1

The source in Coulomb's law is a scalar (electric charge), while the source in the Biot–Savart law is a vector (current element I dl). This vector nature of the source is why the magnetic field also depends on angle.