Answer:
The current needed is 2387.32 A
Step-by-step explanation:
Given;
strength of the magnetic field, B = 1.5 T
length of the solenoid, L = 18 m
diameter of the solenoid, D = 75 cm = 0.75 m
diameter of the superconducting wire, d = 2 mm = 0.002 m
The number of turns of the solenoid is calculated as;

The magnetic field strength is given by;

Where;
I is the current needed
μ₀ is permeability of free space = 4π x 10⁻⁷ T.m/A

Therefore, the current needed is 2387.32 A