Find number of turns in the solenoid

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Homework Help Overview

The problem involves determining the number of turns in a solenoid based on parameters related to an electron's motion within the solenoid. The context includes variables such as the speed of the electron, the diameter of its circular path, the length of the solenoid, and the current flowing through it.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of equations related to magnetic fields and circular motion. There is an attempt to substitute values into these equations to solve for the number of turns, with some questioning the validity of obtaining a fractional turn.

Discussion Status

Some participants have provided guidance on the calculations and expressed concerns about the interpretation of the results, particularly regarding the feasibility of a fractional number of turns. The discussion is ongoing, with participants sharing their calculations and seeking clarification on the problem's parameters.

Contextual Notes

There is a mention of the specific conditions under which the electron moves, including the diameter of its path and the length of the solenoid, which may influence the calculations and assumptions being made.

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Homework Statement


I have the following information about the problem.

i have the speed of an electron = v
the diameter of a circular path = d
the length of a solenoid = x
the current that the solenoid carried = I

I need to find the number of turns in the solenoid.

Homework Equations



i used the following equations
QvB=v2m/r

B=\muNI/l

The Attempt at a Solution



then i put "B" in the first equation and i solve for N. Is that correct?
 
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Yes, do that.
 


the only weird thing is that i get a number like

.121

and it is not a turn .121? or it can be a valid answer?
 


jackxxny said:
the only weird thing is that i get a number like

.121

and it is not a turn .121? or it can be a valid answer?

no, you can't really get less than one. Post the numbers and your working and we'll see if you went wrong anywhere.
 


v=1570 m/s
d = 1.57 cm
x = 35 cm
I = 2.61 A
what I did is :
N=(vmx)/(rQI*4*pi*10^-7)
 


I get the same answer as you, so I guess you'll need to put what you get and round up and put N=1
 


the problem really states...

...that the electron follows a circular path of diameter 1.57 cm near the center of an evacuated solenoid of length 35 cm .

does that changes anything?
 

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