How Does Back EMF and Induced Current Change in a DC Motor's Rotation Cycle?

[zebra1707]

Homework Statement

Describe with the aid of diagrams how the back emf and induced current vary in a single-coil DC motor over one full rotation of the armature.

Give particular attention to the rate of change of flux in the coil and to the direction(s) of the DC and induced current during each quarter cycle.

Homework Equations

No math solution required

The Attempt at a Solution

Im having a great deal of trouble in trying to fit all the elements of this question into a diagram - can someone please assist me with a simplified diagram re the first phase of the rotation - I can do the rest. The one I have is just a mess.

Cheers

 

[anathema]

Hello,

I would be happy to assist you with creating a simplified diagram for the first phase of rotation in a single-coil DC motor. Please see the attached diagram for reference.

In the first phase of rotation, the armature of the motor is in the vertical position, with the north pole of the permanent magnet facing towards it. The armature is connected to a DC power source, which causes a current to flow through the coil in a counter-clockwise direction, as shown by the red arrows.

As the armature begins to rotate, the rate of change of flux in the coil increases. This is because the armature is moving towards the permanent magnet, causing the magnetic field to become stronger. This increase in flux induces a back emf in the coil, which is represented by the blue arrow in the opposite direction of the current.

The direction of the induced current is shown by the green arrows, which are pointing in the opposite direction of the DC current. This is because the induced current is always in opposition to the change in flux.

I hope this diagram helps to clarify the first phase of rotation in a single-coil DC motor. Let me know if you have any further questions or need assistance with the remaining phases of rotation.