Use the expression: ( )F q v B ,= ×   to define the SIunit of magnetic field.

The expression F = q(v × B) is the equation for the magnetic force on a moving charge in a magnetic field. Here:

• F is the force (measured in Newtons, N)
• q is the charge (measured in Coulombs, C)
• v is the velocity (measured in meters per second, m/s)
• B is the magnetic field (measured in Tesla, T)

The equation can be rearranged to solve for B:

B = F / (q × v)

From this, we can see that the SI unit for the magnetic field, the Tesla (T), can be defined as:

1 Tesla = 1 Newton / (1 Coulomb × 1 meter/second)

So, the Tesla is equivalent to a Newton per Coulomb meter per second (N/(C·m/s)).