Physics
Name______________
14.2 / 14.3 / 15.2 wks
Period _____________
De Stigter
Mirror and Lens Equation
20
1
𝑝
+
1
𝑞
1
=𝑓
Mirror and Lens Magnification Equation 𝑀 =
ℎ′
ℎ
𝑞
= −𝑝
1. An incoming ray hits a flat mirror. If the angle of incidence is 38 degrees, what is the angle of
reflection?
2. Suppose you are holding a flat mirror and standing at the center of a giant clock face built into
the floor. Someone standing at 12 o’clock shines a beam of light toward you, and you want to
use the mirror to reflect the beam toward an observer standing at 5 o’clock. What should the
angle of incidence be to achieve this? What should the angle of reflection be?
3. A concave spherical mirror has a focal length of 10.0 cm. Locate the image of a pencil that is
placed upright 40.0 cm from the mirror. Find the magnification of the image. Draw a ray
diagram to confirm you answer.
4. A concave shaving mirror has a focal length of 33 cm. Calculate the image position of a cologne
bottle placed in front of the mirror at a distance of 93 cm. Calculate the magnification of the
image. Is the image real or virtual? Is the image inverted or upright? Draw a ray diagram to
show where the image forms and how large it is with respect to the object.
5. An object is placed 30.0 cm in front of a converging lens and then 12.5 cm in front of a diverging
lens. Both lenses have a focal length of 10.0 cm. For both cases, find the image distance and
the magnification. Describe the images.
6. Complete the following Table:
f
P
q
M
-3.0 cm
?
?
Converging Lens
6.0 cm
2.9 cm
?
?
7.0 cm
Diverging Lens
-6.0 cm
4.0 cm
?
5.0 cm
?
?
?
0.50
7. Sherlock Holmes examines a clue by holding his magnifying glass (with a focal length of 15.0 cm)
10.0 cm away from an object. Find the image distance and the magnification. Describe the
image that he observes.
8. An object is placed 20.0 cm in front of a diverging lens of focal length 10.0 cm. Find the image
distance and the magnification. Describe the image.
9.
Draw a model of how a fiber optic cable works. What speed do the rays inside of it travel?