m(t)=m0*2^(-t/T)
m(t)/m0=m0*2^(-t/T)/m0=2^(-t/T)=1/2^(t/T)=1/2^(30/71)~1/2^(1/2)=sqrt(2)/2=0,705(70,5%)
m(t)=m0*2^(-t/T)
m(t)/m0=m0*2^(-t/T)/m0=2^(-t/T)=1/2^(t/T)=1/2^(30/71)~1/2^(1/2)=sqrt(2)/2=0,705(70,5%)