Scholarships and Awards
for Majors in Physics and Astrophysics
20 Awards available, $1,000 - $10,000
recognizing
Academic achievement,
Potential for excellence in research,
Overall excellence and achievement.
Free Pizza Information Session:
Feb. 29, 5:30 pm, PAN110
Information and application:
http://www.physics.umn.edu/
Application Deadline: March 28, 2016
Undergraduate Research (UROP)
$1500/project
Benefit: a strong letter for the above awards and applications to graduate schools
Getting ready for the first paper
On 2/26 (F) evening after all
students finish their first lab
period of the third assigned lab,
an e-mail will be sent out. Then
you have to send me your choices
of the topics for the paper #1,
along with the UMx500 ID’s of
your lab partners of each topic. I
will assign and e-mail you the
topic for your paper #1. Before 8
AM on 3/1 (Tu), your choice of
the topic should be made.
By now, I sincerely hope that you have the records of your lab partners’ UMNx500 ID's.
The information is required to fill-in your choices of topics for both papers.
Important dates (part of the list)
• Peer Review (first paper): March 8 (Tuesday)
If you are late for the class, most likely you will not be allowed to
participate in the peer-review. By missing the grades of the first draft and
peer-review, your maximum score will be 80% of the paper #1.
• Due time for the revised first scientific paper along with the peer review
report and first draft: noon, March 11 (Friday)
• No Lab Week: March 7-11 (the week before Spring Break)
Next week lecture will be “key components of writing a scientific paper.
Another excellent suggestion from a student
Upon receiving one student’s suggestion, the following e-mail
message was sent to you yesterday morning:
To effectively use the lecture time, please make sure that you have a pen and
a piece of paper to write down the answer(s) of the question(s) for all future
lectures.
Once I call your name or pick you (after raising your hand), you have to show
us that you have one piece of paper with your answer. Previously a few
students got to the white board and tried to figure out the answer(s) by
reading the question(s) on the PPT. It is not a good idea to have the rest of
students waste their time waiting for your answer(s).
Expected equation for thermal expansion:
Before using “black box” software, it is wise to estimate the parameters the oldfashion graphical way first
The initial guess yields
intercept/slope
Least-Square Fit
Black Box: Excel spreadsheet LSQFit
• Read the documentation! Don’t worry about detailed understanding of the inner
workings yet.
• Step 1 is to enter
data manually into
LSQFit or copy
from another
spreadsheet.
• Step 2 is to “fill
down” columns E
through O to
complete LSQFit on
the input data.
• Step 3 is to interpret
the results. a, b, sa,
sb, 2, reduced 2,
M, etc.
LSQFit
spread
sheet
• Step 3 is to
interpret.
Given the initial set of data along with
the LSQFit results, on your paper write
down the fitting results (a and b) with
proper values of errors. Three students
has been picked to write their answers
on the white board.
Fitting data to a straight line
Fitting to this equation,
yields
Write down your answer in your paper with proper values of errors. Use the
calculator in your phone. Two students have been picked to write their answers
on the white board.
Fitting data to a straight line
Fitting to this equation,
yields
Answers:
LSQFit
spread
sheet
What are the meanings of 2, N, M,
reduced 2?
We will not discuss Cov(a,b), rab, and
Sx/S.
Analyses
Once the fitting is done, in general, it is good idea
to exam the quality of fitting through
analyses.
Question: Are there problems
associated with this set of data?
Analyses
The fitting results shown in this figure look very good.
Analyses
However, from the i-plot shown on the right, one immediately
realizes that there is a problem. Question: What is the problem?
Analyses
Once the fitting is done, in general, it is good idea
to exam the quality of fitting through
analyses.
Good data: randomness; most data
having i between -1 and +1
Fitted errors:
i
Measured errors: si
Randomness (good); i too small.
Question: error bars too large or small?
Analyses
Each Geiger counter output, there is error which we do not measure. Thus the lab
manual suggests that you analyze data with respect to a well-established
distribution function (
), then vary si such that 2 has a value of about what?
Plotting data using Excel program
Enter the data
in one Excel
spread sheet,
previously
discussed data
Plotting data using Excel program
Enter the data
in one Excel
spread sheet,
from previously
discussed data
Please raise you hand high, if you already know how to get this figure
from the given set of data using Excel or other programs.
Plotting data using Excel program
Height light B column (x) and
C column (y).
Click on “Insert” tab
Plotting data using Excel program
Under “Insert” tab
Click on “Scatter” tab
Select this choice
Plotting data using Excel program
A scattered
data plot will
show in the
Excel sheet.
Click on the
plot to get the
“Chart Tools”
For a single set
of data, let us
remove the
unnecessary
legend.
Clicking on
“Series1”
Then select
“Delete”
Plotting data using Excel program
Select “Layout”
tab,
Click on “Chart
Title”
Pick “Above
Chart”
Then type the
title of the
figure
accordingly
Plotting data using Excel program
Similarly,
Select “Layout”
tab,
Click on “Axis
Titles”
Pick “Horizontal
Axis Title” and
then
“Vertical Axis
Title” for the
latter one select
“Rotated Title”
Type the “Axis
Titles” of the
figure accordingly
Plotting data using Excel program
Adding
error bars.
In “Layout”
tab,
Click on
“Error
Bars”
Pick “More
Error Bars
Options”
Plotting data using Excel program
This screen will
show up to “format
error bars”
Select “Custom”
then click on
“Specify Value”
Plotting data using Excel program
This screen will
show up.
You have to input
the locations of
positive (negative)
error value in your
spread sheet. They
are in the column D
(highlighted)
Input
=Sheet1!$D$2:$D$16
for both positive
(negative) error
values. Then Click
“OK”
Sheet1
$D$2
$D$16
Plotting data using Excel program
Even though the error bars
on x are not given, the final
plot will show.
Click on one of the
horizontal “error bars” and
then hit “delete”
Plotting data using Excel program
In most cases, this will be
your final plot.
In some cases, you have
more than one set of data
and would like to use
“open” legend instead of
“solid” one. Use the
following instructions.
Right click on one of the
data point.
Plotting data using Excel program
The select “Format
Data Series”
Plotting data using Excel program
In the new
screen
Select “Maker
Fill”
In another new
screen,
Pick “No fill”.
Plotting data using Excel program
Here is our final plot.
Plotting data using Excel program
But the plot of this type is not uncommon in both lab-books and submitted papers.
Can you tell us what are the problems?
Plotting data using Excel program
If the axis labels are too
small, you should click on
one of the number, e.g., “1”
in the horizontal axis, all the
numbers in the horizontal
axis will be in a box.
Then you can change the
font size properly, e.g. from
8 to 12.
Repeat it for the vertical axis
label.
Plotting data using Excel program