A thin lens is made of glass with the refractive index n=1.5 The first side of the lens is plane and the second one is convex spherical with the radius R=30cm . What is the focal length f of the lens? Please select one answer option f=45cm f=60cm f=20cm f=15cm

To find the focal length of the lens, we can use the thin lens formula: Given:- - \( R_1 = \infty \since side is plane)- cm (convex spherical surface)Substituting these values into the formula: Since : Since the focal length is negative, that the focal point is on the same side as the light source, which is typical for a convex lens. Therefore, the correct answer is: