How Small Is It - 02 - The Microscopic (1080p)
Δημοσιεύτηκε στις 3 Δεκ 2014
Text at http://howfarawayisit.com/documents/
In this segment of our “How small is it” video book, we cover the microscopic world.
We
start with optical microscopes and take a look at some of the things
that you can see with light. We also cover light diffraction and show
how it sets a limit on the size of objects we can see.
To
understand how we can go further than light can take us by using
electrons, we cover wave-particle duality. For that we cover particle
momentum and wave interference.
For a closer examination of
waves, we show the famous Young Double Slit experiment that illustrates
the wave nature of light. We also cover Airy Disks as a wave effect to
further illustrate the limits of light microscopes. Then we go deeper
into the nature of electromagnetic radiation. Here we show how it is the
very nature of empty space with its permittivity and permeability that
determines the speed of light in a vacuum.
For the particle
nature of light, we cover Blackbody Radiation, the radiation catastrophe
and how Planck solved the problem by showing that light is created in
integer multiples of a constant now called Planck’s constant. We then
cover Einstein’s photo-electric effect that showed that light was
absorbed in the same multiples of light quanta. We now call these light
quanta photons.
To reconcile these two views of light, we return
to Young’s double slit experiment and fire photons one at a time. The
interference pattern appears over time. We cover how Louis Broglie
extended this wave-particle duality to include electrons and other
particles, and calculated the Broglie wavelength. The conclusion is that
objects interact at points like a particle, but travel through space as
a wave.
We then dig a little deeper into the nature of an
electron starting with J.J. Thompson’s discovery using a mass
spectrometer. With the electron’s mass known, we calculate its
wavelength and find it much smaller than an optical photon’s wavelength.
This makes it ideal for breaking through the diffusion limit to see
much smaller objects.
We end by covering how a scanning electron microscope works and using it to view very small things - down to a carbon atom!
STEM
In this segment of our “How small is it” video book, we cover the microscopic world.
We
start with optical microscopes and take a look at some of the things
that you can see with light. We also cover light diffraction and show
how it sets a limit on the size of objects we can see.
To
understand how we can go further than light can take us by using
electrons, we cover wave-particle duality. For that we cover particle
momentum and wave interference.
For a closer examination of
waves, we show the famous Young Double Slit experiment that illustrates
the wave nature of light. We also cover Airy Disks as a wave effect to
further illustrate the limits of light microscopes. Then we go deeper
into the nature of electromagnetic radiation. Here we show how it is the
very nature of empty space with its permittivity and permeability that
determines the speed of light in a vacuum.
For the particle
nature of light, we cover Blackbody Radiation, the radiation catastrophe
and how Planck solved the problem by showing that light is created in
integer multiples of a constant now called Planck’s constant. We then
cover Einstein’s photo-electric effect that showed that light was
absorbed in the same multiples of light quanta. We now call these light
quanta photons.
To reconcile these two views of light, we return
to Young’s double slit experiment and fire photons one at a time. The
interference pattern appears over time. We cover how Louis Broglie
extended this wave-particle duality to include electrons and other
particles, and calculated the Broglie wavelength. The conclusion is that
objects interact at points like a particle, but travel through space as
a wave.
We then dig a little deeper into the nature of an
electron starting with J.J. Thompson’s discovery using a mass
spectrometer. With the electron’s mass known, we calculate its
wavelength and find it much smaller than an optical photon’s wavelength.
This makes it ideal for breaking through the diffusion limit to see
much smaller objects.
We end by covering how a scanning electron microscope works and using it to view very small things - down to a carbon atom!
STEM
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