text: physics problem, help!? you have a telescope that is made up of a small convex mirror (on the left) facing a larger concave mirror (on the right) that is 0.75 m away. the larger concave mirror has a hole in the center to allow the reflected light from the convex mirror to make an image that is on the other side of the concave mirror. the concave mirror has a radius of curvature of 2.0 m and the smaller of 60 cm. how far from the smaller mirror (to the right of both the mirrors) should the film plane be located if the object is a star? use lens maker's formula 1/f = (n-1)(1/r1-1/r2) but use n=-1 as the "refractive index" as light travels with same speed but in opposite direction so f=0.5*r1*r2/(r2-r1)        (here r1 is  -ve and r2 is +ve)      f= 0.857 m since the star is at "infinity" , the light rays will focus at 0.857m from convex mirror or 0.107 m from concave