Your labs will require you do several different things: simulate
circuits, construct them, characterize them (measure voltages and
currents), and compare your measurements results with the results
from the simulation and expectations based on the reading.
Your lab report should show that you did all these things and it should
demonstrate that you understood the concepts behind the circuits and
- You should have a good idea what results you
should get before you start.
- Setting up experimental circuits requires that you
pay attention to details. A single wrong connection will still give you
results. But they will virtually always be different from the ones you
should have observed. If you don't know what to expect, you won't know
when it is wrong.
- Electronic components fail.
- A burned out fuse on a voltage supply line is
only easy to find if you look for it. But if you don't know that your
results are wrong, you will not look for it.
- A burned out diode or transistor is not
going to tell you that it is broken. If you don't know what to expect,
you will not know that they were blown.
- If you just follow the instructions, take data, and
then try to make sense of all this later when you go to write up your
lab report, you will be surprised at how little sense your data makes.
- How will you know what to expect?
- Review and seek to understand the circuits in the
lab manual before you come to class.
- Helpful in that will be to read the relevant book
sections and the lecture notes, and finally,
- use the simulation software to "build" the
circuit and simulate its behavior.
- During the experiments:
- Besides measuring voltages at the outputs you may
find it useful to measure voltages at other locations in the circuit
and consider if these make sense.
- It is often useful to modify the circuit a bit,
to check if the result changes as expected. For example: A transistor
is often used to amplify a current. But this can only work if its
collector terminal is powered. Disconnect the power to the collector.
If nothing changes, your transistor is probably faulty.
Parts of a Lab Report
Organize your information:
- The Title identifies the major topic of your
- You are the Author and your lab partner is
listed as "partner."
- Author: John Doe, Partner: Jane Doe
- In case you did parts of the lab alone or with a
different partner because your original partner missed parts of the
class, mention here which parts you did alone or with a different
- The Abstract the gives a very brief
(150-200 word) description of what is covered in the report.
- Subheading, indicate each section.
Generally, each lab consists of a series of small experiments. For
example, in Lab. 2 you build a simple AC voltage divider, observe the
RC decay of an RC circuit on different timescales, investigate a CR
high pass, RC
low-pass, and LR filters, investigate an LRC resonant circuit and
finally build a tank circuit Fourier analyzer. Cover each of these
experiments completely as described in the
following sub-bullets before describing the next experiment.
- Give a sentence or two about the motivation for
experiment (section): What is the goal? As motivation for the
circuits built you can take the approach that you are seeking to
confirm the physics embodied in the expressions used or to confirm the
circuit behaviors expected from the textbook readings (with appropriate
citation to those).
- Circuit diagram: This can be a copy of the
circuit built in the simulator.
- It should include the names and values of all
clearly identify the output nodes in your circuit.
- Add a list of components used in the form
of a table. Use the actual values wherever possible (as measured
resistances or capacitances).
- Measured voltages from DC power supplies
should be listed as well.
- Experimental Procedure: In your own words
describe the measurement process referring to the
circuit diagram(s). If the order in which things were done is relevant
to the procedure/result then give the temporal order but otherwise
avoid using irrelevant temporal phrases. This experimental procedure
include your measurement of the resistors, capacitors, and supply
voltages listed above (we'll assume you did this correctly). Do not
copy text from the lab manual to the report. Describe what you actually
did (not what the manual says you were supposed to do). If your
procedure deviated from the instructions given in the
manual state that. If you've
written this up properly another reasonably intelligent researcher
should be able to follow your description to do what you did and get
- Results: This should include results from
the simulations, relevant screenshots of your scope image, and data
from your measurements in neat tables and plots .
- Graphics need to be clear, easily read, and well
labeled (e.g., "Figure 3: RC filter circuit", "Figure 4: Measured
voltage amplitude as a function of frequency for the RC circuit of
Figure 3"). Every figure and table that appears in the report must be
called out in the text of the report. For example: "To investigate the
behavior of a CR filter the circuit shown in Figure 3 was
assembled. The frequency response of its voltage amplitude was both
simulated and measured from 10 Hz to 100 kHz. The measured result is
shown in Figure 4, the simulation in Figure 5." One
very common mistake is that the axes of 'screenshots' from the
oscilloscope are often not labeled correctly.
- Compare your results with your expectations.
Plots should include the data as data points and a curve based on the
expected result should be fitted to the data if possible.
- Include a brief discussion of how the circuit
works. Show that you understood the experiment. We will not be
concerned with experimental error in this course. That will be dealt
with (in spades) in PHY4803L.
- Summary/General discussion:
- At the end give a general summary of what can be
said about the larger set of experiments, but keep it short. There are
no bonus points for long reports. Labs should be 6-8 pages.
- Lab Report Guidelines
- Use proper English: write in complete,
grammatically correct sentences. Use a spell checker.
- Label all figures and tables with a descriptive
- e.g., "Figure 1: Output from a high-pass filter,
using as input a 60 Hz, 2 V, square wave. R = 10k, C =
- Show the complete analysis of your work. "Yes." is
never accepted as an answer.
- Example: the lab asks you if the output from a
circuit is what you expect. "yes" or "no" is not appropriate.
Appropriate would be: "We expected the half-wave rectifier circuit
would pass only
the positive swing of the input AC voltage. The input AC
and output voltages were fed to channel 1 and 2 of the scope,
respectively. The input AC showed both the positive and negative going
voltage swings, while the rectifier output showed the positive swings
when the input was positive and was flat line zero during the negative
swings thus matching our expectations."
- Show the data needed to support your statements.
- If the lab manual asks you to show something you
need to show the data, or a screenshot or a plot that demonstrates the
trend. Simply saying we observed the thing that was asked for will not
- Answer all questions for each part of the lab.
Please ask if you aren't sure if something should be answered. Put the
questions and the answers in the part of the report where they are
- Lab partners results should be consistent. You should
have the same images and the same data points (2.90 and 2.88 are fine.
2.02 and 2.19 are not). If there are any issues sharing information
please let the instructors know.
- If you miss a day, you may not copy data taken by
your lab partner while you were absent. You will need to repeat those
measurements yourself at a time when your partner does not need the
equipment. Sections of the report where the data was taken
independently should be identified.