T=1f\mathrm{T}=\frac{1}{f}T=f1
T=f\mathrm{T}=fT=f
T=1f2\mathrm{T}=\frac{1}{f^2}T=f21
f=1 T2f=\frac{1}{\mathrm{~T}^{2}}f= T21