Lab 13: Focal Length of Lens
Muhammad Khan
Nick Kasecky
Amber Honsaker
PHYS 2426
24 April 2019

Intro:
The focal length of a spherical lens may be determined by use of the Fundamental Lens
Equation.
1
p
+
1
q
=
1
f
The magnification of the image is given by the equation.
M
=
h
i
h
o
=
−
q
p
We will use these eqautions in our lab to complete our data table. The first equation also known
as the Lens maker Equation is widely used in optometry. The second is the magnification
equation which will let us know if the image is magnified or is smaller then the original object
height.
Procedure:
●
Set up the equipment as shown in the figure. Place the object, the crossed arrow target, on
the front of the light source.
●
Put the lens 500 mm from the light source, ie. Object distance p=500 mm.
●
Move the viewing screen back and forth until the image is in focus. Measure the image
distance and image height.
●
Record the image distance, q, and height, hi, in the data table. Calculate the focal length
and magnification, and record these.