Question

Plz answer this I have board exams.... Plzzz

Answer 1

since the optical device makes the light rays converge at a single point it is CONCAVE lens

the point where all the parallel light rays converge is the focus

so the distance between screen and mirror gives you the focal length which is 15-2 = 13 cm

radius of curvature = 2( focal length)

R = 13× 2= 26cm