The image of the moon is focussed by a converging lens of focal length 50 cm on a plane screen. The image is seen by an unaided eye from a distance of 25 cm. Find te angular magnificatioin achievd due to the converging lens.

Answer

`2`

Explanation

In Fig. moon subtended an angle `alpha` on the lens. This would be the angle subtended by moon on the eye, when viewed directly.

As is clear from Fig.
`beta = x//d` and `alpha = x//f`
`:.` Angular magnification
`m = (beta)/(alpha) = (x//d)/(x//f) = (f)/(d) = (50)/(25) = 2`