Answer:
The value is [tex]N =36203 \ turns[/tex]
Explanation:
From the question we are told that
The length of the solenoid is [tex]l = 0.56 \ m[/tex]
The magnetic field is [tex]B = 6.5 \ T[/tex]
The current is [tex]I = 80 \ A[/tex]
The desired temperature is [tex]T = 4.2 \ K[/tex]
Generally the magnetic field is mathematically represented as
[tex]B = \frac{\mu_o * N * I }{L }[/tex]
=> [tex]N = \frac{B * L }{\mu_o * I }[/tex]
Here [tex]\mu_o[/tex] is the permeability of free space with value
[tex]\mu_o = 4\pi * 10^{-7} N/A^2[/tex]
So
[tex]N = \frac{6.5 * 0.56 }{ 4\pi * 10^{-7} * 80 }[/tex]
=> [tex]N =36203 \ turns[/tex]