- physics textbook, paper, pencil
Remember school material on the main magnetic laws.Open physics textbook grade 9 and see paintings depicting the magnetic field of the permanent magnets.As is known, the magnetic field itself is generated by charge carriers in the case when they are moving.This, in fact, the principle of action of the motor.It is known that, if introduced into the magnetic field of a current carrying conductor last begins to deviate as if the magnetic field pushes the conductor itself in a certain direction.When current is not flowing through the conductor, the field does not perceive it.The force acting on current-carrying conductor, called the Lorentz force.The action of this force is based on the action of a magnetic field on moving charged particles in the conductor, which form
an electric current.
Take a sheet of paper and a pencil and draw two rectangles, spaced a certain distance from each other.One rectangle write the letter "C" and the other "U".Two of the rectangle will be two permanent magnets used in electric motors DC.Draw the magnetic field lines that extend from the north pole of the magnet to the south (the direction of the lines can be indicated by arrows).Imagine now that in this field with a current conductor made perpendicular to the lines of magnetic induction.The Lorentz force acting on charges in a conductor, this conductor pushes out of the magnetic field.The direction of action of the force depends on the direction of the current in a conductor.And if you change the direction of current is reversed, the direction of the Lorentz force also is reversed.
Imagine that you make in a given magnetic field of two conductors with currents in opposite directions.Then one of the wires will be pushed to one side, and the other - in the opposite direction.When applied to such two conductors forming a certain cylinder, arranged opposite each other with respect to the axis of symmetry of the cylinder, the cylinder and placed in a magnetic field, the magnetic field is expressed in the fact that the cylinder is rotated by an angle of 90 degrees.If there are such guides on a cylinder often and periodically change the direction of the current in the conductors, the rotation of the cylinder will be carried out at smaller angles and become smoother.Thus the motor is realized.