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Electricity and Magnetism question

  • Thread starter matt85
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  • #1
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A solenoid 2.9 cm in diameter and 15 cm in length has 300 turns and carries a current of 5 A. Calculate the magnetic flux through the circular cross-sectional area of the solenoid.


-->> I tried using the equation B = u(0)NI/L to calculate magnetic field, and then putting this in the formula flux = BNA, where N is number of turns, and A is area (pi*r squared). This didn't work, though.

I'd appreciate some help!!! Thanks!
 

Answers and Replies

  • #2
The field is indeed given by
[tex]B=\frac{\mu_{0}NI}{L}[/tex]

and the total flux through the solenoid
[tex]\phi=NAB[/tex] is also right.

Maybe what they asked for is the flux through a single turn which would be your answer divided by N

Also keep in mind that
[tex]B=\frac{\mu_{0}NI}{L}[/tex]
is valid only for a long solenoid. (When its length is large compared to its radius)

I feel your solenoid is long enough. I don;t see why you're not arriving at the answer.
 
  • #3
25
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yep, it was wanting it through one turn. thanks.
 
  • #4
mukundpa
Homework Helper
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matt85 said:
... Calculate the magnetic flux through the circular cross-sectional area of the solenoid....

I think NBA is the total flux linked with the solenoid, not the flux through the cross-section. It is BA only.


MP
 

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