The questions and their equations are provided

Book reference is Magnetic Resonance Imaging: Physical Principles and Sequence Design (2nd ed.), R. W. Brown, Y-C. N. Cheng, E. Mark Haake, M.R. Thompson, R. Venkatesan, John Wiley & Sons, Inc., Publications, 2014

Problem 4.2 The key equation (4.12) can be used to investigate general questions. If unmagne- tized material is placed in a region with a finite static field at t = 0 (M.(0) = 0): a) Find the time it takes, in units of T;. for the longitudinal magnetization to reach 90% of M. b) Find an approximate formula for M, (t) of this material in the limit that t