A B field, also known as a magnetic field, is a region in space where a magnetic force can be detected. It is created by moving electric charges and can affect other moving charges within its vicinity.
The strength of a B field can be measured using a device called a magnetometer. This device measures the force exerted by the B field on a magnetic needle or other test object.
The strength of a B field is affected by the magnitude and direction of the electric current producing the field, as well as the distance from the source of the field. It can also be affected by the presence of other magnetic fields.
The direction of a B field is determined by the direction in which a compass needle points when placed in the field. The needle will align itself with the direction of the field lines, which always point from north to south.
The B field at a specific point can be calculated using the formula B = μI/2πr, where μ is the permeability of the medium, I is the current producing the field, and r is the distance from the point to the current. This formula is known as the Biot-Savart law.