Question

A convex meniscus lens is made of glass with refractive index, n= 1.5. The radius of curvature of the concave surface is 46.2 cm and the radius of curvature of the convex surface is 22.4 cm.

a)Calculate the focal length of the lens.
b)Determine the position of the image of an object which is placed 2.0 m in front of the lens.

Answer 1

n2/n1

Answer 2

n=1.5
r1=22.4cm
r2 = 46cm
a)
(1/f) = (n-1) ( (1/r1) -(1/r2))
(1/f)= (1.5-1) ((1/22.4) - (1/46) )
f= 87.32 cm
focal length of lens is 87.32 cm