energy as waves?
Published on Nov 24, 2015
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energy as waves?
wave is disturbance or oscillation (of a physical quantity), that travels through matter or space, accompanied by a transfer of energy.
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surface waves in water
They consist, instead, of oscillations or vibrations around almost fixed locations
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Quantum Theory!
energy acts like particles that come in small packets. can't break apart. like marbles in a bag. when take a marble out, taking out a packet of glass, not a single glass, but a bunch of glass in one packet
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E = hv
E = energy
v = frequency
h = 6.626x10^-34 (Planck's constant)
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at end of 1800s waves and particles very different. waves disturbances in space, could pass through and interfere with each other
particles: definite boundaries, bounced off each other when collided, only in whole number quantities
Planck considered crazy for a little while.
Until...
Einstein!
26 year-old clerk in Swiss patent office. Wrote 5 papers, one of which used quantum theory to explain photoelectric effect. Only way to understand was see light as packets of energy. later called photons. 1921 given nobel prize in physics for photoelectric effect
particles: definite boundaries, bounced off each other when collided, only in whole number quantities
Planck considered crazy for a little while.
Until...
Einstein!
26 year-old clerk in Swiss patent office. Wrote 5 papers, one of which used quantum theory to explain photoelectric effect. Only way to understand was see light as packets of energy. later called photons. 1921 given nobel prize in physics for photoelectric effect
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Niels Bohr
Believed rutherford's nuclear atomic model and used quantum theory to save it.
Said energies associated with electrons orbiting the nucleus had similar restrictions.
Said energies associated with electrons orbiting the nucleus had similar restrictions.
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Spectroscope separates light into wavelengths.
Unique bright-line spectrum for each gaseous element.
Sealed glass tube with a gas, like hydrogen, apply high voltage across electrodes, gas heats and emits light.
using spectroscope, saw series of colored lines against black background
using spectroscope, saw series of colored lines against black background
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Quantum physics:
Bohr's Postulates
Bohr's Postulates
Bohr's postulates
- Certain allowed energy levels.
- Electron moving in allowed orbit did not absorb energy
- Electron moves from one orbit to another if absorbed or emitted energy
1. corresponded to circular electron orbit of certain size. larger orbit, great energy. no other orbits in atom. each energy state given quantum number: 1, 2, 3, etc. Lowest called ground state, larger called excited states.
1&3 explain bright line spectrum: atomic spectrum not continuous because atom's energy states only certain values. When gas heated, electrons jump, once in higher energy orbit, can return to lower by emitting energy
1&3 explain bright line spectrum: atomic spectrum not continuous because atom's energy states only certain values. When gas heated, electrons jump, once in higher energy orbit, can return to lower by emitting energy
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Quantum Mechanics:
Particles acting like waves
Electrons like packets of energy ...waves behaving as particles. (5.2)
But particles also act like waves. Bohr's theory only worked with hydrogen, not with more than 1 electron.
Louis de Broglie: gave a reason why electron's had fixed energy levels.
But particles also act like waves. Bohr's theory only worked with hydrogen, not with more than 1 electron.
Louis de Broglie: gave a reason why electron's had fixed energy levels.
Photo by Gwydion M. Williams
String theory
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