A solenoid used to produce magnetic fields for research purposes is 2.2 mm long, with an inner radius of 30 cmcm and 1200 turns of wire. When running, the solenoid produced a field of 1.4 TT in the center. Given this, how large a current does it carry?

The current is  

Explanation:

From the question we are told that

    The length of the solenoid is  

    The  radius is  

    The number of turn is

    The  magnetic field is  

The  magnetic field produced  is mathematically represented as

making the subject

Where   is the permeability of free space with values

 substituting values

i think the answer is a and b

i wish you luck