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Redish’s Proposal for 132 Content (bio-related)

My proposal for the second semester of the course differs from the one listed in the original HHMI proposal in that it attempts to integrate the biological issues throughout and selects topics in a way that the physics builds naturally.  The main difference with traditional courses is that it assumes a semester of chemistry as a prerequisite.  As a result, the concept of atoms and molecules are included from the first and electrical forces are integrated with the discussion of gravity.  Thermal topics and chemical energies are included at an early stage and the basics of diffusion and osmosis are discussed in conjunction with the discussion of heat transfer.  Authentic biological examples will be included throughout, with much of that work being done through complex problem solving for homework.  (Complex problem solving outside of class is one of the prime pedagogical tools to be utilized.)

In the second semester, this base can be built upon.  Traditionally, the second semester would include the following physics topics.

• Oscillations and Waves
• Simple harmonic oscillator, [pendulum, damped and driven oscillators]
• Examples: Gait 
• Transverse waves on strings and springs
• [Longitudinal waves in materials – sound]
• Fields (vector and scalar, i.e., forces and potentials)
• Gravitational
• Electric
• Magnetic
• Electrical Applications
• Devices – batteries, resistors, capacitors [, inductors]
• Ammeters & Voltmeters
• Network analysis, Kirchoff’s laws
• [Electromagnetism]
• [Electromagnets]
• [Faraday’s law]
• [Devices – mass spectrometer, cyclotron, Van de Graff generator]
• Properties of Light
• Geometrical optics
• Wave optics
• [Electromagnetic model of light]
• [Photon optics]
• [Quantum Properties of Matter]
• [Wave properties of matter]
• [The interaction of matter and light]
• [Black-body radiation]
• [Spectra]
• [Photoelectric effect]
• [Atomic levels and molecular bonding]

In traditional courses, this is far too much to cover.  The topics in square brackets [..] are often omitted. 

Here is my current schedule of covering these topics:

Week 1: Simple harmonic oscillator

Week 2: Transverse waves on strings

Weeks 3 & 4: The ray model of light; Images and optical devices

Week 5: The wave model of light

Week 6: Electric forces [would be covered in semester 1]

Week 7: Fields

Week 8: Electric potential and voltage

Weeks 9 and 10: Electric circuits, currents, Kirchoff’s laws, capacitance

Week 11: Magnetism

It is hard to imagine doing any of these topics in a shorter time, as students find them all difficult and confusing and all have value.  Here are a few comments about my experience teaching these topics with the cases for and against their inclusion.

Oscillations and Waves

This stuff is basic and critical as metaphor for many phenomena.  It’s hard to imagine a course without it being accepted anywhere in the country as a “physics” course.  There are lots of applications and it has good competency building components.

•   It helps nail down the concepts of forces, energy, and the relation between them.
• It is an excellent place to develop the students’ sense of mechanism, bridging a picture of the physical phenomenon with multiple representations – diagrams, equations, and graphs of a variety of different physical variables.
• Since we will have calculus, this is an excellent place to start with basic differential equations and their role in scientific modeling.

We can probably do simple harmonic motion, transverse waves, longitudinal (sound) waves, and light together with interference in 3 weeks.  There are many devices that play a role in biological measurement (sonograms, interferometers, etc.) that could serve as extended problems.

Geometrical Optics

It might be best to drop geometrical optics, though I would do so with reluctance, since it has a number of valuable competency building components:

•  It allows one to begin with everyday experience, discover misconceptions and inconsistencies in one’s everyday interpretations and learn how to refine and reconcile intuition.
•  It allows one to build convincing basic principles from everyday experience and learn how to do complex reasoning leading to surprising (and correct) results.
•  It provides a number of different representations (ray diagrams, equations) that can be coordinated.
•  It uses equations to express relationships rather than as an obvious and direct calculational tool.  It is a good place to learn to use equations as a qualitative reasoning tool.
• It provides the basic information as to how many of the measuring devices they will use work.
•  It is the fundamental physics for a significant branch of pre-med students – ophthamologists.

On the other hand, it is reasonably self-enclosed.  Removing it can be done without negatively affecting any other topics.  Perhaps we could create a few modules on the topic that could, for example, be used at the beginning of Karen’s class, assuming they have had the rest of the physics.

Electricity

Electric forces, instruments, and models are critical for many topics in biology, especially at the cellular level.  We certainly must provide a base for understanding electric issues in cells and as the tools for the modeling that will take place in an upper division neurophysiology course.  If electric forces and potential energies are covered in the first term, that will give a good base for (after a brief review) an introduction to the concept of fields – electric (vector) and electric potential (scalar).  These are conceptually difficult and I strongly encourage us not to rush through them. 

Electrical devices are also difficult – even in the traditional framing intended for engineers.  For this class, I would encourage us to expand the frame and look at situations where thermal energy and diffusion are balanced against electrical forces.  (Perhaps the Nernst equation belongs here instead of in the first term.)  Electrical phenomena in fluids should be introduced.

Even with moving some of electricity to the first term, I would encourage us to think of spending at least three weeks on this topic – maybe 3.5.

Magnetism

Electromagnetism

Quantum Physics