(1) \(\tau=\frac{L}{c}=\frac{120m}{3*10^8m/s}=4*10^{-7}s\)

(2) \(\Delta \mu=\frac{1}{\tau}=\frac{1}{4*10^{-7}}=2.5*10^6\)

(3) \(\Delta \lambda=\frac{\lambda^2}{L}=\frac{(632.8nm)^2}{120m}=3.34*10^{-15}m\)