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Breakthrough Junior Challenge
Course: Breakthrough Junior Challenge > Unit 1
Lesson 3: 2015 Challenge — Physics- Special theory of relativity - 2015 Challenge Winner!
- A visualization of special relativity
- Chromatic aberration
- Orbital mechanics
- What is light?
- Special and general relativity
- The science of fireworks
- Quantum tunneling
- Antimatter
- Special Relativity
- What Einstein missed: The EPR paradox
- Virtual particles and gravity
- Interstellar and Hawking radiation
- All about superconductors
- Entropy and the direction of time
- Magnetism, light and the magneto optic Kerr effect
- The theory of everything
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Magnetism, light and the magneto optic Kerr effect
By Joseph Copland.
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If photons don't have mass, but have energy, then they can't fit E=mc^2? What am I missing?(5 votes)
E=mc^2 shows how energy can be transformed into mass.
so for a photon with an energy of 2 eV (electron volts, a measure of energy)
2=m(299,792,458^2) divide both sides by c^2
2/89875517873681764=m
a photon of 2eV can be transfered into approximately 2.22530011210723686×10^(-17) grams(5 votes)
- @1:20"Light amplitude" is tricky. A singular photon does not have an amplitude. Photons are "wave like", not wave functions. Photons are wave like in that they have wavelengths, but a singular photon does not have an amplitude.
Physicist say that the amplitude, or luminosity, of a beam of light of many photons is the number of photons in a given amount of time. Luminosity is also directly related to intensity which is a reference to the total amount of energy in a beam of light in a given amount of time to a given area of surface. But this "amplitude" is not derived from a physical amplitude of a wave function, rather it is just a useful analogy. Thus photons are wave like and not waves.
You need to be more specific when you say "light" especially since you then go on to specifically talk about a singular photon. Amplitude of light is only a useful analogy the present of many photons. Amplitude has no special meaning to a singular photon. I feel your presentation of this fact is confusing and likely misleading to new students of the subject.
@3:50Coherence should be wavelength or frequency, since one will give the other. If you say "wavelength and frequency", you will confuse new students on the subject since you seem to infer the properties are somehow different instead of different ways to measure the same physical phenomenon.(0 votes)
1:20