Electromagnetic Radiation

In this lecture I explain why light particles (photons) are referred to as electromagnetic radiation by discussing their wave-like behaviour and how it is associated with their electric and magnetic fields. I also describe the many properties of photons, including wavelength, frequency, and amplitude, and make clear how these particles transfer energy. Finally, I explain how the spectroscopy methods of emission and absorption spectra work, how they can be used to identify elements, and why they are related to the concept of a quantum, and the study of quantum mechanics. Included in this video are concepts such as bight line and dark line spectra, energy levels, ground states, and excited states.

[jefflyon]

This series of lectures paired with Professor Jason Kendall's introductory astronomy lectures is a awesome example of how the internet can expand your understanding of the world we live in, nature and space/time, and the 4 fundamental forces than govern our universe, no college application to send or tuition to pay, it is all up to you.these fine teachers just help clarify things, thank you Bio-chem geek for such clear lessons.

[nannygee]

Finally someone that makes sense! Never thought I’d understand this stuff

[harrishkarunakaran]

If biochem geek has a million fans, I’m one of them. 
If biochem geek has five fans, I’m one of them.
If biochem geek has one fan i’m that one. 
If biochem geek has no fans, that means I am no longer on this earth.
If the world is against biochem geek, I am against the world.

[juliavixen]

I've found myself answering a lot of people's questions about optics and QM lately... and, so I'm really lamenting about how introductory EM is taught. This video is all the standard explanations, and it's ok for chemistry, and I think it confuses a lot of people when they start to learn QM, or Relativity, or just reason out a bunch of physical processes. (oh, and classical EM theory too.) But also, this video would be more than 37 minutes long trying to cover some of the other stuff, but it might be worth adding a few minutes to clarify that things like the photon are a very useful abstraction, and the EM field is continuous and a chaotic mess, that light transfers momentum from an accelerated charge to a distant charge, the EM field just being the potential energy at any arbitrary point in space, what light actually "looks like" (the picture everyone draws is the electric potential as a sine wave and the magnetic potential as a sine wave perpendicular to the other one and direction of motion, but in physical 3D space (not potential energy phase space) it's a series of blobs, um... blackbody radiation... radio antennas... capacitance and inductance... Fourier analysis... anyway, there's a lot more going on, and to learn it people need to unlearn thinking about light as little tiny particles, and electrons as tiny balls moving in a circle around the nucleus (ok, they'll get this later in chemistry class (I hope)). (Yeah, yeah, I know Compton scattering, etc.)

Because people want to know what is "really happening".

P.S. Gilbert N. Lewis came up with the name "Photon".

[kevinmorgan]

(EM radiation or EMR) is a form of energy emitted and absorbed by light particles (called photons)? Surely EMR the photons??

[planmet]

I can't understand why no-one - other than myself - sees the sinusoidal wave as the movement of particles in a helical motion. This interpretation allows for photons to behave both as a wave and as particles. The radius of the helix would still represent the amplitude - and the wavelengths would remain the same. And in the slit experiments - only particles at appropriate points in their helical motion would pass through the slit while others would hit the sides of the slit.

[tonymarshharveytron]

Hello, I have to disagree. All electromagnetic radiation does not travel as waves, unless it is made to travel as a wave artificially. Electromagnetic radiation travels in discrete quanta in a straight line with frequency, but not amplitude, just like a bullet fired from a gun. The frequency is the number of these quanta passing a given point in a given time, the greater the number per second the higher the frequency and energy.

In rays of light and radiation from the Sun, there is frequency, but not amplitude. The stream of radiation produced in a ' Cathode Ray Tube ' does not have amplitude, although the beam can be made to occilate by external magnets. Kind regards,

Tony Marsh.