[填空题]
A laser beam is direct 2y7,ttj*k ujmed at the Moon, 380,000 km from Earth. The beam/wb+ ( l a5u:wqwck-4njc-oy r diverges at an an(lqrwcj :4n5/-a b- wwo+ckyugle $\theta$ (Fig. 8–37) of $1.4\times10^{-5}$ rad What diameter spot will it make on the Moon? m
Post time 2025-2-18 20:00:22
