Two-lens optical system focal point · CAP 2005 #25

Physics · optics

Problem

Light rays from a very distant source travel along the

+x

direction. Two identical thin lenses with focal length

f > 0

and their optical axis along

x

, sit, one at

x = 0

, and the other at

x = d < f

. Where do the rays focus? (a)

d + \frac{f(f-d)}{2f-d}

; (b)

d - \frac{f(f-d)}{d}

; (c)

d + \frac{f(f-d)}{2(f+d)}

; (d)

d + \frac{f^2}{2f-d}