"Don't spend time beating on a wall, hoping to transform it into a door."
--Dr. Laura Schlessinger
Preparation
Pre-lab assignment 12 (*.html)
(Due 12:00 PM before start of lab)
Equipment
digital multimeters (voltmeter/ammeter/ohmmeter, 2 per group)
thin wire, 2-m long, insulation stripped at ends
PASCO Scientific PI-9587C Digital Function Generator-Amplifier
connecting banana plug wires (black, red)
RadioShack 273-104 Snap-On RF Choke (for transformer core) (*.html)
connecting banana plug wires (black, red)
alligator clips
Digital Multimeter Setup and Equipment Notes
(These instructions do not need to be included in your step-by-step procedure.)
To measure potential difference, turn dial from "off" to "V (straight/squiggly line)." Plug wires into the "COM" and "V-Ω" sockets, and connect these wires in parallel to the circuit component of interest. After you are done, turn the dial back to the "off" position.
Function Generator Setup and Equipment Notes
(These instructions do not need to be included in your step-by-step procedure.)
Connect leads to the "Low Ohm" and "GND" plugs. Turn the "Amplitude" knob all the way to the left. Turn on the function generator, and dial the frequency to 60.0 Hz. (The "Sine Wave" function should be selected by default; if not, then toggle the "Waveform" buttons.) Set the input voltage ε1 to 0.50 V.
Research Question
Build a transformer with N1 primary turns of wire and N2 secondary turns of wire. Connect the function generator to the primary side of the transfer. Set up a voltmeter (to measure the input voltage ε1) in parallel with the function generator on the primary side of the transformer, and a voltmeter (to measure the output voltage ε2) on the secondary side of the transformer.
Investigate how the output voltage is affected by varying the number of primary turns and second turns, and/or varying the alternating current frequency.
Tasks
- Procedure
Write a step-by-step procedure on a whiteboard. Instructor will check it off for full credit before data collection. (It is okay to do some preliminary scratch work.) Procedure should be detailed enough for another Physics 205B student to reproduce your results, without having to "fill in the blanks." Instructor may instead make suggestions or corrections that need to be completed before your group can receive full credit.
- Data
Record your data on another whiteboard. Instructor will check it off for full credit before laboratory ends. Data should be detailed enough for another Physics 205B student to understand what relevant quantities were measured for interpretation later. Graphs may be plotted by hand on graph paper, or printed out from a computer.
Make sure you have a copy (hand-written, smartphone photo, etc.) of your instructor-checked procedure and instructor-checked data before cleaning up equipment and leaving laboratory today.
Report Format
- Procedure
- Data
- Discussion/Conclusion
Describe how the data is used to answer the research question. Discussion should be detailed enough for another Physics 205B student to reproduce your results, given similar data.
Your report should include all three parts, manuscript format (double-spaced neat writing or typed; equations/calculations can be written in by hand). Due at the end of next laboratory. (Reports up to one week late are graded for half-credit. No reports accepted more than one week late.) Additional credit awarded for instructor verifiably receiving report during the first 10 minutes of next laboratory.
Preparation/Reflection Points
1 = Pre-lab reading assignment (graded for completion)
1 = Post-lab reflection assignment (graded for completion)
Report Points (due at end of next lab, +1 bonus for early submission)
1 = Procedure (graded for completion during lab)
1 = Data (graded for completion during lab)
3 = Discussion/Conclusion/Report
3 = Complete, thorough, understandable
(Reproducible by another student from start-to-finish.)
2 = Minor, "resolvable" omissions--acceptable effort
(Some common-sense/intuitive steps missing.)
(Another student would need a few minutes in order to "fill in the blanks.")
1 = Major "problematic" omissions--minimally acceptable effort
(Some essential/critical steps missing.)
(Another student would need to ask questions in order to "fill in the blanks.")
0 = Unacceptable or no significant effort beyond original in-lab work
1 = Early bonus for report received by instructor up until first 10 minutes of next lab
Follow-up
Complete this week's lab report and post-lab assignment, next pre-lab assignment (due in two weeks, after spring break), and review lab instructions.
Due 12:00 PM before start of next lab
Post-lab assignment 12 (*.html)
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