Answer:
it's C and D... do you understand?
Answer:

Explanation:
Potential difference between two points in constant electric field is given by the formula

here we know that

also we know that

now we have

now change in potential energy is given as



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.
Explanation:
Wind Currents. currents of the surface waters of oceans and seas resulting from the action of wind on the surface of the water: Wind currents arise owing to the combined influence of the forces of friction, turbulent viscosity, pressure gradient, deflecting force of the earth's rotation, and so on.