PASCO OS-8515C Basic Optics System - Manual (Page 39)

®
M o d e l N o . O S - 8 5 1 5 C Experiment 13: Focal Length and Magnification of a Concave Mirror
39
Analysis Part A: Focal Length
1. Calculate 1/d
o
and 1/d
i
for all six rows in Table 13.1.
2. Plot 1/d
o
versus 1/d
i
and find the best-fit line (linear fit). This will give a straight
line with the x- and y-intercepts equal to 1/f. Record the intercepts (including
units) here:
y-intercept = 1/f = _______________
x-intercept = 1/f = _______________
Note: You can plot the data and find the best-fit line on paper or on a computer.
3. For each intercept, calculate a value of f and record it in Table 13.2.
4. Find the percent difference between these two values of f and record them in
Table 13.2.
5. Average these two values of f. Find the percent difference between this average
and the focal length that you found in Part I. Record these data in Table 13.2.
Analysis Part B: Magnification
1. For the last data point only (d
o
= 25 cm), use the image and object distances to
calculate the magnification, M. Record the results in Table 13.3.
(eq. 13.2)
2. Calculate the absolute value of M using your measurements of the image size and
object size. Record the results in Table 13.3.
(eq. 13.3)
Table 13.2: Focal Length
f
Result from x-intercept
Result from y-intercept
% difference between results from intercepts
Average of results from intercepts
Result from Part I
% difference between Average of results from intercepts and result from Part I
M
d
i
d
o
-----
⎝ ⎠
⎜ ⎟
⎛ ⎞
– =
M
image size
object size
------------------------- =