It doesn't. We do.
We rotate in such a way that the sun looks like it is rising and falling, but it really isn't.
Answer
Correct Answer is B(to change direct current into alternating current)
Explanation
commutation
The main aim of commutation is to maintain the torque acting on armature of DC motros in the same direction.
commutator a switch which is used to convert the direction of flow of electric current it is connected to the armature of DC motor.
In DC motors, voltage across the armature is alternating in nature. The direction of this current is reverses by Commutator when armature of DC motors passes through magnetic neutral axis to maintain the unidirectional. Hence, commutator is used to change direct current into alternating current.
According to the gravitational force law, force existing between two objects is proportional to the mass of the two objects and inversely proportional to the square of the distance between them. When masses are doubled each. Then the force increases 16 times.