[填空题]
A laser beam is dire,d 2a5rvj)vu u. *2 kw;q3pt1) -vjxbvufehffcted at the Moon, 380,000 km from Earth. The beam diverges at an anglebt1uk) w;qf23f.v-fp xh ej v* $\theta$ (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
