Department of Physics
University of Lagos
B.Sc. (Hons) Degree Program
Course: Geometric Optics
Code: PHS 227
DUE DATE: 11th April 2023
HM 3
ATTEMPT ALL
Student Assignment as Part of the Continues Assessment towards the final Grade.
1. An object that is 5 cm high is placed 70 cm in front of a converging lens whose focal
length is 20 cm. Determine the characteristics of the image
2. An object is located 80 cm to the left of a concave mirror of radius 50 cm. Calculate
(a) the power of the mirror, (b) the position of the image, and (c) its magnification.
3. An object is located 10 cm to the left of a convex mirror of radius 30 cm. Calculate
(a) the power of the mirror, (b) the position of the image, and (c) its magnification.
4. An object whose height is 4 cm is placed 50 cm from a diverging lens. If the focal
length of the lens is 30 cm, determine the characteristics of the image
5. A converging lens of focal length 12 cm is placed 52 cm from another converging
lens of focal length 8 cm. Calculate the image position of an object that is 16 cm in
front of the first lens.
6. An equiconvex lens 2 cm thick having radii of curvature of 4 cm is mounted on one
end of a water tank. An object in air is placed on axis 10 cm to the left of the lens
vertex. The indices are 1.00, 1.50, and 1.33 for air, glass, and water respectively.
Find the: (a) final image position, (b) the size of the image, (c) the equivalent power
of the lens.
7. An object is placed 0.5 m away from a concave mirror of focal length +1.0 m. The
image formed by the mirror is
Use the diagram below to answer questions
8. If the distance of an object Q is 5m below the pool as it is shown, at what distance
will image of Q ie (Q’) appear to be for the swimmer above the pool?
9. A biconvex lens of 5 cm thickness and index 1.60 has surfaces of radius 40 cm. If
this lens is used for objects in water, with air on its opposite side, determine its
effective focal length and sketch its focal and principal points.
10. A double concave lens of glass with n=1.53 has surfaces of 5D (diopters) and 8D,
respectively. The lens is used in air and has an axial thickness of 3 cm. (a)
Determine the position of its focal and principal planes. (b) Also find the position of
the image, relative to the lens center, corresponding to an object at 30 cm in front of
the first lens vertex. (c) calculate the paraxial image distance assuming the thin-lens
approximation. What is the percent error involved?
11. A biconcave lens has radii of curvature of 20 cm and 10 cm. Its refractive index is
1.50 and its central thickness is 5 cm. Describe the image of a 1-in. tall object,
situated 8 cm from the first vertex.
12. An equiconvex lens having spherical surfaces of radius 10 cm, a central thickness of
2 cm, and a refractive index of 1.61 is situated between air and water (n=1.33). An
object 5 cm high is placed 60 cm in front of the lens surface. Find the cardinal
points for the lens and the position and size of the image formed.
13. A hollow, glass sphere of radius 10 cm is filled with water. Refraction due to the
thin glass walls is negligible for paraxial rays. (a) Determine its cardinal points and
make a sketch to scale. (b) Calculate the position and magnification of a small
object 20 cm from the sphere.
YOUR PAPER WILL NOT BE GRADED IF SUBMITTED AFTER THE DUE DATE
EXPIRED.