*A sample has a T*_{1} of 1.0 seconds. If the net magnetization is set equal to zero, how long will it take for the
net magnetization to recover to 98% of its equilibrium value?
Given: T_{1} = 1.0s

The relationship between the equilibrium net magnetization, M_{o},
and the net magnetization, M_{z}(t), at time t is:

M_{z}(t) = M_{o}(1 - e^{-t/T1}).

When M_{z}(t) / M_{0} = 98%:

0.98 = M_{z}(t) / M_{0 }= (1 - e^{-t/T1})
0.98 = 1 - e^{-t/T1}
1 - 0.98 = e^{-t/T1}
ln( 0.02 ) = -t/T1
-T_{1} * ln( 0,02 ) = t
-1.0s * ln( 0,02 ) = **3.9s = t**