With the help of telescope that has an objective of diameter 200 cm. it is proved that ligh of wavelengths of the order of 6400 `Å` coming from a star can be easily resolved. Then, the limit of resolution is

Options

A. `39 xx 10^(-8)` deg
B. `39 xx 10^(-8)` rad
C. `19.5 xx 10^(-8)` rad
D. `19.5 xx 10^(-8)` deg

Answer

b

Explanation

The limit of resolution of a telescope is
`theta = (1.22 lambda)/(d)`
Where, `lambda` = wavelength of light rays
d = aperture of objective lens of telescope.
Here, `lambda = 6400 Å = 6400 xx 10^(-10) m`
`d = 200 cm = 2 m`
Substitution of value gives
`theta = (1.22 xx 6400 xx 10^(-10))/(2)`
`= (1.22 xx 64 xx 10^(-8))/(2)`
= 1.22 xx 32 xx 10^(-8)`
`= 39 xx 10^(-8)` rad