Videos tagged physics
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PY106 pre-class video for session 40 - The de Broglie wavelength
In this video, we spend some more time on wave-particle duality. We have already addressed the idea that light, in some situations, exhibits a wave nature; in other scenarios, it exhibits a particle nature. Here, we discuss a similar duality [...]exhibited by things like electrons, which we usually think of as particles. In particular, we will talk about various situations in which "particles" exhibit a wave nature.
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PY106 pre-class video for session 37 - Thin-film interference
In this video, we cover the basics of thin-film interference. This is interference between light reflecting from the two surfaces of a thin film. A good example is a soap bubble - the beautiful colors in a soap film are explained by thin-film [...]interference. We start by going over what happens when a wave is partly transmitted and partly reflected - in some cases, the reflected part of the wave reflects upright, and in other cases it reflects upside-down. We look at the basic idea of thin-film interference, and then we go through a five-step method we can apply when we analyze a thin-film situation.
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PY106 pre-class video for session 26 - Standing waves
In this video, we discuss the physics of standing waves, which is directly relevant to musical instruments. In particular, we focus on standing waves on strings that are fixed at both ends, which is how strings are set up on stringed instruments.
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PY106 pre-class video for session 24 - The Doppler effect
In this video, we introduce the Doppler effect, which is the shift in frequency caused by motion of the source, or the observer (or both), of waves. We will derive the general equation for the Doppler effect for sound waves, and the video will also [...]include several animations to help illustrate why there is a frequency shift when either the observer or the source moves.
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PY106 pre-class video for session 22 - Electric generators
In this video, we take a quick look at electric generators - devices that generate electricity by exploiting Faraday's law. At its heart, a generator is a pretty simple device - it is a conducting loop in a magnetic field. By rotating the loop, the [...]magnetic flux changes, and a current is induced in the loop. We'll explore the details of how this is done in the video.
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PY106 pre-class video for session 21 - Motional emf
Here's another relatively short video, introducing the concept of motional emf. That is voltage induced across the length of a conductor that is moving through a magnetic field. If you place such a conductor in a circuit, it will act like a battery, [...]giving rise to an induced current.
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PY106 pre-class video for session 19 - Lenz's law, and a pictorial approach
In this video, we go over Lenz's law, which is a law that relates to the minus sign in Faraday's law. Faraday's law tells us that a changing magnetic flux will produce an induced voltage. Lenz's law tells us about the direction of the induced current [...]in a loop or coil because of that induced voltage. There's a pictorial method for figuring out the direction of this induced current, so we'll spend a good part of this video on that.
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PY106 pre-class video for session 18 - Magnetic flux, and Faraday's law
In this video, we introduce the concept of magnetic flux, and then we go on to talk briefly about Faraday's law. Faraday's law is incredibly important from a practical sense, particularly for the generation of electricity. Almost all ways to generate [...]electricity, with the exception of solar photovoltaic systems (solar panels) and batteries, exploit Faraday's law.
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PY106 pre-class video for session 13 - The force on a charge in a magnetic field
In this video, we look at the force that is experienced by a charged particle in a magnetic field. We compare this to the force experienced by a charged particle in an electric field, and we also go through a number of different scenarios to see what [...]the magnetic force is determined by. In the end, we come up with an equation for the magnitude of the magnetic force, and we finish up with a discussion of the right-hand rule, which we use to determine the direction of the force.
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