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 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
Back
Top