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PY106 pre-class video for session 32 - Refraction
In this video, we discuss the basics of refraction, which commonly refers to the change in direction a beam of light generally experiences when it passes from one medium to another. The reason for a change in direction is that the speed of light [...]depends on the medium, so the speed of the light usually changes when the light changes medium. In the video, we will define the index of refraction; talk about a simple model of refraction; and go over Snell's law, which is an equation we apply to refraction.
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PY106 pre-class video for session 27 - Radiation pressure
In this video, we discuss the energy and momentum carried by an electromagnetic wave. Regarding energy, we often talk about the intensity (power per unit area) associated with an electromagnetic wave. When we talk about momentum, we often talk about [...]radiation pressure - pressure associated, for instance, with a beam of light shining on an object. The video wraps up with some calculations related to solar sails, which are spacecraft that use radiation pressure for propulsion.
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PY106 pre-class video for session 25 - The interference of waves
In this video, we talk about the interference of waves, and look specifically at constructive and destructive interference. We also look at the fact that interference is all about superposition - the net result is simply the sum of the individual [...]waves. Finally, we end the video with a discussion of beats, which is a nice application of constructive and destructive interference.
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PY106 pre-class video for session 23 - Waves
In this video, we'll start talking about waves. This is our first introduction to the topic - we'll do a lot more on waves in upcoming videos. This time, we'll talk about transverse and longitudinal waves, and then we'll look at the equation we use [...]to describe a single-frequency transverse traveling wave. Finally, we'll wrap up the video by looking at how we measure wavelength and period.
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PY106 pre-class video for session 20 - Faraday's law, and the flux vs. time graph
This is another relatively short video, focused on the connection between induced current and the flux vs. time graph. By working with Faraday's law and Ohm's law, we will look at the various pieces of information you can extract from such a graph, [...]including how to compare the magnitude of the induced current at different times; how to get information about the direction of the induced current; and how to do a calculation of the magnitude of the induced current at a particular instant in time.
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PY106 pre-class video for session 12 - Kirchoff's rules
In this video, we cover the loop rule and the junction rule, which are collectively known as Kirchoff's rules. The junction rule states that the sum of all the currents coming into any point in a circuit is equal to the sum of all the currents going [...]away from that point. The loop rule states that the sum of all the potential differences around a complete loop in a circuit is zero. We will make use of these rules to calculate the current in a circuit that has one battery and three resistors. Note that we again make use of the Circuit Construction Kit Phet simulation from the University of Colorado, available at http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
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PY106 pre-class video for session 10 - Resistors in parallel; resistors in series
We begin this video with a discussion of electric power, and discuss how you go about calculating how much an electrical device costs to run. We then go through the derivation of the equation to calculate the equivalent resistance of resistors in [...]parallel, as well as a similar derivation to find the equation for the equivalent resistance of resistors in series. For both resistors in parallel and resistors in series, we look at an animation of the process, and also discuss the relevant ski-hill analogy. Note that these animations use the circuit construction kit simulation, which is one of the Phet simulations from the University of Colorado. The link to that simulation is http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
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PY106 pre-class video for session 9 - Current, batteries, and resistance
In this video, we start talking about the basic building blocks of electric circuits. We will define current, and go through how a battery works. We will also talk about resistance, and Ohm's law, which connects voltage, current, and resistance. The [...]movie wraps up with an introduction to a ski-hill analogy for an electric circuit.
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PY106 pre-class video for session 8 - Capacitors
In this video, we talk about various issues related to capacitors, which are devices that can store electric charge (and, because they store charge, they store electrical energy, too). Our focus will be on the parallel-plate capacitor, which you can [...]make by connecting two cookie sheets to a battery. We'll talk about the capacitance of a parallel-plate capacitor; the electric field between the capacitor plates; the energy stored in the capacitor; and the effect of adding a dielectric (a piece of insulating material) to the space between the plates. Note that the simulation that was used to generate the animations used in the movie is available in Chapter 17 at the Essential Physics web site, located at http://physics.bu.edu/~duffy/EssentialPhysics/
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