PHYC 110
Physical Science
Name _______________
Date ________________
Exercise 12: Light and Optics
Speed of light in a vacuum c =3.0x108 m/s
1. The index of refraction of glass is 1.5. How fast does light travel through glass?
n = 1.5
n = c/v
c = 3.0x10
n = 1.5 = c/v = 3.0x108/v
v = c/n = 2.0x108 m/s
2. The speed of light in a particular type of glass is measured to be 1.60 x 108 m/s. What is
the index of refraction of this glass?
v = 1.6x10
n = c/v
c = 3x108
n = c/v = 3.0x108/1.60x108 = 1.85
3. Sketch a ray diagram for a spherical convex lens with an
object at a distance (20 cm) twice the focal length (10 cm)
from the lens (see figure). Describe the image characteristics:
a. real or virtual
b. upright or inverted
c. increased in size or reduced in size
d. Estimated distance from lens.
a. real
b. inverted
c. about the same
d. 20 cm.
4. A light ray strikes a flat mirror with a 30-degree angle of
incidence. Draw a ray diagram to show how the light ray
interacts with the mirror. Label the normal line, the
incident ray, and the reflected ray.
5. Light, being a transverse wave, can be polarized. Can
sound waves be polarized? How would it sound?
Sound is a longitudinal wave and cannot be polarized.
incident ray
reflected ray