Description
Prove with the help of Lenz’s law, why the rotation of the motor changes when the connections of the armature are reversed?

Explanation & Answer

Lenz's law is a common way of understanding how electromagnetic circuits obey Newton's third law and the conservation of energy. Lenz's law is named after Heinrich Lenz, and it says:
An induced electromotive force (emf) always gives rise to a current whose magnetic field opposes the original change in magnetic flux.
Lenz's law is shown with the negative sign in Faraday's law of induction ,which indicates that the induced emf and the change in magnetic flux have opposite signs
http://en.wikipedia.org/wiki/Lenz%27s_law
