Simple Fleming Question

Physics and electronics discussion, revision, exam and homework help.

Announcements Posted on
Enter our travel-writing competition for the chance to win a Nikon 1 J3 camera 21-05-2013
IMPORTANT: You must wait until midnight (morning exams)/4.30AM (afternoon exams) to discuss Edexcel exams and until 1pm/6pm the following day for STEP and IB exams. Please read before posting, including for rules for practical and oral exams. 28-04-2013
Sign in to Reply
  1. Charries's Avatar
    • Exalted Member
    • Posts: 269
    Simple Fleming Question
    OK - the answer to this question is downwards using FLHR

    Click image for larger version. 

Name:	photo(19).JPG 
Views:	17 
Size:	77.5 KB 
ID:	150033

    But i get a bit confused when the show positive charges- could they equally.

    1. show electrons moving in the same direction as the attached image, and if so would the force still be downwards?

    2. If they showed a wire in a circuirt with a cell, do I assume current flows from the larger | to the smaller | of the cell (hope you know what I mean), which will get me current direction.
  2. Pangol's Avatar
    • Benevolent Member
    • Posts: 683
    Re: Simple Fleming Question
    The direction of the current in Fleming's Left Hand Rule is conventional current. If you know how the relates to electron flow, you should be able to answer your first question.

    In a circuit diagram, the longer bar represents the positive side of the cell, the shorter bar the negative. Again, if you know the definition of the direction of flow of conventional current, you should be able to answer your second question.
  3. Charries's Avatar
    • Exalted Member
    • Posts: 269
    Re: Simple Fleming Question
    OK - conventional curent positive to negative, as a pd across plates would flow.

    I can now answer my second question but not my first. Are you saying that if they stated the particle was negatively charged and pointing into the plane of the paper, I would reverse the direction (or are you simply saying they wouldn't show an electron?)
  4. Pangol's Avatar
    • Benevolent Member
    • Posts: 683
    Re: Simple Fleming Question
    (Original post by Charries)
    Are you saying that if they stated the particle was negatively charged and pointing into the plane of the paper, I would reverse the direction
    Yes, of course. You correctly say that conventional current flows from positive to negative. This is the opposite direction to the flow of electrons in a wire. Removing the wire, and just dealing with a flow of free electrons, doesn't change this. Electrons flow one way, conventional current flows the other way.
  5. Charries's Avatar
    • Exalted Member
    • Posts: 269
    Re: Simple Fleming Question
    OK - thank you. If I see electrons moving in one direction, I change that direction and use Fleming. Ta.
Sign in to Reply
Share this discussion:  
Article updates
Moderators

We have a brilliant team of more than 60 volunteers looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Reputation gems:
The Reputation gems seen here indicate how well reputed the user is, red gem indicate negative reputation and green indicates a good rep.
Post rating score:
These scores show if a post has been positively or negatively rated by our members.