Presentation on theme: " When a current moves through a conductor in a magnetic field a force is produced. Michael Faraday discovered that the force on the wire is at right."— Presentation transcript:
When a current moves through a conductor in a magnetic field a force is produced. Michael Faraday discovered that the force on the wire is at right angles to both the direction of the magnetic field and the direction of the current.
Faraday’s explanation was lacking the direction of the force. The force can be found by using the Third right-hand rule. Point right hand fingers in the direction of the magnetic field Point thumb in the direction of conventional current Palm points in the direction of force
Experiments show that the magnitude of the force, F, on the wire, is proportional to the strength of the field, B, the current, I, in the wire and the length, L, of the wire in the magnetic field F=ILB B is the strength of the magnetic field measured in teslas, T (1 T = 1N/A. m
Charged particles don’t have to be confined to a wire, they can also move in a vacuum. These are called cathode-ray tubes used to form pictures on screens. Magnetic fields control the motion of the beam (back & forth, up & down) The screen is coated with phosphor that glows when it is struck with the electrons
The force produced by a magnetic field on a single electron depends on the velocity of the electron and the strength of the magnetic field. F=qvB q is the charge measured in Coulombs v is velocity measured in m/s B is magnetic field strength measured in T The direction of the force is given by the third right-hand rule keeping in mind the rule is for positively charged particles, so for electron the force would be opposite.