Magnetic resonance imaging needs a magnetic field strength of 1.5 T. The solenoid is 1.8 m long and 75 cm in diameter. It is tightly wound with a single layer of 1.90-mm-diameter superconducting wire.
a. What current is needed?

2270 A

Explanation:

First, the number of turns in the solenoid

where l is the length and d is the diameter of a single layer. In this case, the number of turns will be

The current, I round solenoid will be given by

where B is the magnetic field strength, L is the length of solenoid, is permeability of free space and N is the number of turns. Taking the permeability of free space as

when it gains or loses electrons

increase masses, decrease separation