The focal length of the objective and eye piece of a telescope are respectively `100 cm and 2 cm`. The moon subtends and angle of `0.5^@`, the angle subtended by the moon's image will be.

Options

A. `10^(@)`
B. `25^(@)`
C. `75^(@)`
D. `100^(@)`

Answer

B

Explanation

Here, `f_(0) = 100 cm, f_(e) = 2 cm`
`alpha = 0.5^(@), beta = ?`
As `m = (f_(0))/(f_(e)) = (beta)/(alpha)`
`:. beta = (f_(0))/(f_(e))alpha = (100)/(2) xx 0.5^(@) = 25^(@)`