Measuring the strength of a Magnetic Field © D Hoult 2008

When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is

When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is parallel to the flux lines

When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is parallel to the flux lines The direction of the force is at 90° to both the current and the flux lines

When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is parallel to the flux lines The direction of the force is at 90° to both the current and the flux lines Fleming’s left hand rule helps to remember the relation between the three directions…

Thumb First finger Second finger

ThuMb Motion First finger Second finger

ThuMb Motion First finger Field Second finger

ThuMb Motion First finger Field SeCond finger Current

Factors affecting the Magnitude of the Force The force depends on

The force depends on - the current flowing through the conductor, I

The force depends on - the current flowing through the conductor - the length of conductor in the field

The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that

The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I

The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L

The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L F = I L × a constant

The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L F = I L × a constant magnetic field strength or

The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L F = I L × a constant magnetic field strength or magnetic flux density

F = I L B

F = I L B units of B Newtons per Amp per meter, NA-1m-1

F = I L B units of B Newtons per Amp per meter, NA-1m-1 1 NA-1m-1 is called 1 Tesla (1 T)

F = I L B units of B Newtons per Amp per meter NA-1m-1 1 NA-1m-1 is called 1 Tesla (1 T) The flux density of a magnetic field is

F = I L B units of B Newtons per Amp per meter NA-1m-1 1 NA-1m-1 is called 1 Tesla (1 T) The flux density of a magnetic field is the force per unit current per unit length acting on a conductor placed at 90° to the field

F = I L B units of B Newtons per Amp per meter NA-1m-1 1 NA-1m-1 is called 1 Tesla (1 T) The flux density of a magnetic field is the force per unit current per unit length acting on a conductor placed at 90° to the field F = I L B sin q