A laser beam passes through a slit of width 1.0cm and is pointed at the Moon, which

Question:

A laser beam passes through a slit of width 1.0cm and is pointed at the Moon, which is approximately 380,000 km from the Earth. Assume the laser emits waves of wavelength 630nm (the red light of a He∙ Ne laser). Estimate the width of the beam when it reaches the Moon.