List of top Physics Questions on Refraction At Spherical Surfaces And By Lenses asked in AP POLYCET

An object placed between the principal focus and center of curvature of a convex lens forms an image:
An object is placed at a distance of $ 30 \, cm $ from a concave lens of focal length $ 20 \, cm $. The image distance is:
A double concave lens of refractive index 1.5 with its two spherical surfaces of radii R1 = 30 cm and R2 = 45 cm is kept in air. Its focal length is