Calaculate the minimum spearation between two points on the Moon which can be resolved by a reflecting telescope with mirror diameter `5m`. The wavelength of light is assumed to be equal to `lambda = 0.55 mu m`.

Explanation

The limit of resolution of a reflecting telescope is determined by diffraction from the mirror and obeys a formula similar to that from a refracting telescope. The limit of resolution is
`(1)/(R ) = (1.22lambda)/(D) = ((Deltay)_(min))/(L)`
where `L =` distance between the earth and the moon `= 384000 km`
Then putting the values `lambda = 0.55mum, D = 5m`
we get `(Deltay)_(min) = 51.6`metre