Electricity & Magnetism > Electric Fields and Potential > Electric Field, Electrostatic Potential and Potential Energy
Electricity & Magnetism > Electrostatics > Multipoles
Highlights:
Students measure an ECG and work out the corresponding moving electric dipole moment of the heart
Abstract:
This resource provides background reading and lecture materials to prepare students to understand the underlying physics behind the electrical signal produced by the beating heart on the body surface, recorded in the form of an electrocardiogram (ECG). Then, in the laboratory, students measure their own ECGs and from their data calculate and display the moving electric dipole moment of the heart that produced that signal. Students should gain a deeper understanding of electric dipoles and how the basic physical mechanism that produces the heart's dipole moment comes from the electrical activity of the heart at the cellular level.
Resource Types:
Student reading, Instructor supplement, Clicker question, Lecture materials, Lab, Homework
Authors:
John W. Hirshfeld Jr., MD
Perelman School of Medicine, University of Pennsylvania
TOPICS
Physics Topics:
Life Sciences Topics:
Human and Animal Physiology > Cardiovascular System > Cardiovascular Disorders, Healthy Cardiovascular Function
Medical Applications > Diagnostic (non-imaging) Techniques > Electrical Diagnostics
FILES
Introduction to the Electrocardiogram
Introduction to the Electrocardiogram
INSTRUCTOR GUIDE
IMPLEMENTATION
Duration: 2 sessions of 3 hours per session.
Equipment required: Specialized physics equipment
Specific equipment needed: List provided, all can be obtained from Vernier.
Basic implementation tips & tricks:
First, the time needed is one 50-minute lecture and one 3-hour lab, with students spending modest additional time reading and answering preparation questions.
The measurement is very quick; the analysis is what takes time. We have tried to lay out a clear explanation of what analysis to do. In principle the students could try to figure out what analysis to do. However, the mathematical derivation is confusing to students because it's quite abstract and uses an approach not used in other electrostatics problems; it's hard to see where it's going. So it's not simple for students to plan their own analysis.
How does this resource fit into the flow of your course? This unit comes at the end of electrostatics, as soon as students have encountered the idea of electric potential. It serves as the final application of electric dipoles.
PEDAGOGY
Pedagogical approach: Peer Instruction / Think-Pair-Share; Collaborative problem-solving; Conceptually-oriented activities; Context-rich problems; Mathematically-focused activities; Experimentally-focused activities
Skills / Competencies: Performing experiments; Analyzing experimental data; Applying physical principles; Interdisciplinarity
What insights or realizations do you hope students gain from this resource? Most importantly, a net electrical signal is only produced when cells are actively depolarizing. Students should understand that any signal in the ECG arises when the heart is actively beating; during parts of the heart cycle when no contraction or relaxation is occurring, the signal is flat. At a more detailed level, the electrocardiogram exploits the fact that an electric dipole has an equipotential along the axis perpendicular to its dipole moment to measure a component of the dipole moment by measuring a potential difference along that axis. Hopefully students will understand this use of the properties of dipoles by the ECG.
Why is this resource useful to life sciences students? This helps students gain a deeper understanding of the electrical mechanism producing the electrocardiogram.
DISCUSSION
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SUBMISSION DETAILS
Copyright: 2019 Catherine Crouch, Ben Geller, John W. Hirshfeld Jr., MD
CC: BY-NC-SA - Attribution, No Commercial uses and Share Alike. Derivative works must have the same licenseLast Edit Date: July 5, 2019
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