[填空题]
A laser beam passes t.*9gxa*tjwprtpui 7 q1yx3.c 4xla.thm 5*wmmix8pg o /q)q/srough a slit of width 1.0 cm and is pointed at the Moon, which is approximately 380,000 km fm m/i/p m*5oxqgs)qw8rom the Earth. Assume the laser emits waves of wavelength 630 nm (the red light of a He-Ne laser). Estimate the width of the beam when it reaches the Moon. km
