DC Electromagnetic Motor-small question

  • Thread starter moshrom
  • Start date
  • #1
11
0

Homework Statement


[PLAIN]http://img695.imageshack.us/img695/206/95144436.jpg [Broken]


Homework Equations


Hand rules


The Attempt at a Solution


This is a practice question with the answer already given in the diagram. I know how to draw the coils and use the left hand rule to find the poles. I do not understand b), though. I know the two north poles repel, but why does A move forward instead of backwards?

Thanks.
 
Last edited by a moderator:

Answers and Replies

  • #2
collinsmark
Homework Helper
Gold Member
2,919
1,318
I do not understand b), though. I know the two north poles repel, but why does A move forward instead of backwards?
I think it has to do with manner in which the brushes are drawn with respect to the rest of the commutator. See the part of the diagram near where "Front" and "Back" are written.

Imagine what would happen if it moved in each direction (A moved forward, and A moved backwards). Consider the impact of the way the brushes/commutator are drawn.
 
  • #3
11
0
Oh okay, I think I get it. Normally the direction can be determined if the armature is drawn slightly turned. I assumed the 'front' and 'back' labels were written as part of the answer, I guess they were originally given. Thanks.
 

Related Threads on DC Electromagnetic Motor-small question

Replies
6
Views
769
  • Last Post
Replies
1
Views
519
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
1
Views
9K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
784
  • Last Post
Replies
13
Views
962
Top