Is this the default set up of a DC motor?

AI Thread Summary
The discussion centers on understanding the default setup of a DC motor, specifically regarding current direction and the application of Fleming's left-hand rule. A participant initially expresses confusion about the absence of direction indicators at specific points in their textbook. Clarifications reveal that current polarity is indicated by the battery and rotor winding arrows, while the magnetic field is marked with N-S labels. It is noted that current flows in the rotor's plane and switches polarity once per cycle. The explanation concludes by emphasizing that the current flow is based on conventional current, moving from positive to negative.
ellieee
Messages
78
Reaction score
6
Homework Statement
in every d.c motor, is it always the case that the current at coil "a" is flowing into the plane and current at coil "d" is flowing out of the plane?
Relevant Equations
-
CamScanner 06-08-2021 10.04.jpg
16231239573775046085477797659441.jpg

^because in my textbook, the set up doesn't even show the direction of dot/cross at points A/D, so we won't know the direction of current. then how are we supposed to use fleming's left hand rule to determine the direction of force?
 
Physics news on Phys.org
I don't understand your question. The current polarity is clearly shown with the battery as well as arrows on the rotor winding. The magnetic field polarity is also shown with N-S labels. The current flows in the plane of the rotor, which is rotating. Then once per cycle, the current switches polarity.
 
DaveE said:
I don't understand your question. The current polarity is clearly shown with the battery as well as arrows on the rotor winding. The magnetic field polarity is also shown with N-S labels. The current flows in the plane of the rotor, which is rotating. Then once per cycle, the current switches polarity.
oh I see it now thank you !
 
The 'Dot', 'Cross' symbols are taken from how a target arrow (as used in archery) looks when viewed from the end. The 'Dot' is the tip of the arrow coming towards you, and the 'Cross' is the fletching (feathers) on the other end of the arrow going away from you.

Note that this is Conventional Current flow, '+' to '-', Not Electron flow.

Hope this helps!

Cheers,
Tom
 
  • Like
Likes 2milehi and ellieee
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Back
Top