A certain superconducting magnet in the form of a solenoid of length 0.56 m can generate a magnetic field of 6.5 T in its core when its coils carry a current of 80 A. The windings, made of a niobium-titanium alloy, must be cooled to 4.2 K. Find the number of turns in the solenoid.

The value  is

Explanation:

From the question we are told that

   The length of the solenoid is  

   The magnetic field is

    The current is

     The desired temperature is  

Generally the magnetic field is mathematically represented as

=>    

Here   is the permeability of free space with value  

So

=>  

iron would move it is magnetic there is a mag field around the current in the wire