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 `0.5^2`, 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_o)/(f_e) = (beta)/(alpha)`
`:. beta = (f_o)/(f_e) alpha = (100)/(2) xx 0.5^@ = 25^@`.