The force acting per unit current per unit length on a current-carrying conductor placed perpendicular to the magnetic field
Rearranging the equation for magnetic force on a wire, the magnetic flux density is defined by the equation:
Note: this equation is only relevant when the B field is perpendicular to the current
Magnetic flux density is measured in units of tesla, which is defined as:
A straight conductor carrying a current of 1A normal to a magnetic field of flux density of 1 T with force per unit length of the conductor of 1 N m-1
To put this into perspective, the Earth's magnetic flux density is around 0.032 mT and an ordinary fridge magnet is around 5 mT
A 15 cm length of wire is placed vertically and at right angels to a magnetic field.When a current of 3.0 A flows in the wire vertically upwards, a force of 0.04 N acts on it to the left.Determine the flux density of the field and its direction.