1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

AC Magnetic Field (solenoid) ID OD L AmpTurns Relationship

  1. Mar 17, 2012 #1
    I am trying to make a .4 Tesla AC (50Hz) magnetic coil. Originally I used ID-38MM, OD-155MM & Length of Solenoid 50MM. Using 3.5MM X 1.5MM wire 380 Turns. I get 0.27 Tesla at 75Amp. but the wire allows me to work only for around 5 Min with Forced air cooling.
    I do not know the relationship how the field will depend on ID,OD & Length (just that the field is directly proportional to Amp Turns).
    It would be great if some could give a conditions for maximum field.

    Any guidance will be great help since i was not able to find anything on NET.
  2. jcsd
  3. Mar 18, 2012 #2
    If no one has an answer can anyone suggest a Book for Ac coils ?
  4. Mar 19, 2012 #3


    User Avatar

    Staff: Mentor

    Hi gosain_sanjay! There are a number of inter-related factors to play with. Is 75A the maximum current you are able to supply? In which case, you can only change coil dimensions and number of turns to gain a stronger field. If your arrangement gets too hot, then you will have to use thicker wire or else use two parallel windings.

    If you double the wire's cross-sectional area, you halve its resistance and the amount of heat produced falls by half, providing current remains the same. However, with the bulkier windings, there is probably less effective cooling so the temperature may not fall by as much as you would hope.

    With such a large current in a large inductance, there is considerable energy stored and this can be hazardous. If a wire should break or a connection come apart, this energy will be released in one giant flash splattering molten copper around. Tight-fitting safety glasses are a must.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook