1. physics; classic vs quantum

7/30/2019 1. Physics; Classic vs Quantum

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Physics: Classic vs. Quantum

Suryadi, S.T, M.T

Sekolah Tinggi Teknologi Indocement


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Outlines

Fisika klasik

Kegagalan fisika klasik

Persamaan Schrodinger Penafsiran fungsi gelombang

Superposisi (dualisme gelombang) dan

nilai harapAplikasi mekanika kuantum


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Fisika Klasik

Materi dan energi adalah dua konsep berbeda.

Sir Isaac Newtons laws of motion

James Clerk Maxwells theory of electromagnetic

radiation Mechanics, dynamics, hydrodynamics, statics,

optics, thermodynamics, acoustics.

Hukum kekekalan massa, hukum kekekalan

energi, hukum kekekalan momentum.

They state that mass and energy can be neither created nordestroyed, and the momentum of an object will only be changed

if an outside force acts on it.


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Fisika Kuantum

Tahun 1900, garis demarkasi berakhirnya fisika klasik.

Max Planck berbicara mengenai small units of energydisebut

quanta.

Teori Relativitas Einstein

Quantum Mechanics

Classical physics can be thought of as physics on a

macro scale; it explains the big, basic things of theworld anddoes notdrill down into the t iny wor ld of

molecules and atomsin order to describe how the

world works.


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THREE FAILURES OF CLASSICAL PHYSICS

1. Blackbody Radiation

2. The Photoelectric Effect

3. The Hydrogen Atom


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Blackbody Radiation

Any object with a temperature above absolute zero emits light at all

wavelengths. If the object is perfectly black (so it doesn't reflect any

light), then the light that comes from it is called blackbody

radiation.

E= hf


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Photoelectric Effect


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Electrons can only absorb energy from

individual photons. Only light with short

enough wavelength has photons with

enough energy to eject an electron.


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The Hydrogen Atom

Classical physics said that because the orbiting electron is constantly

changing direction, it should emit electromagnetic radiation --- light. As a

result, the electron should be continually losing energy. In fact, physicists

calculated that the electron should lose all of its energy and spiral down into

the proton in only about 0.000000000001 second! In other words, atoms

should not exist longer than a mere 10-12 seconds. WRONG!!


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Niels Bohr provided an explanation in 1913. In the Bohr model of the

hydrogen atom, the electron can't orbit the proton in any size orbit it

pleases. There are only certain allowed orbits, and each allowed

orbit has a certain radius and a certain energy.

He said that when an electron is in an allowed orbit, the electron willnot produce electromagnetic radiation.

Question: If the electrons do not produce light when they are in their

allowed stable orbits, where is the source of the light that comes

from hydrogen?

Answer: According to Bohr, electrons have more energy when theyare in larger orbits. If an electron falls from a larger orbit down to a

smaller orbit, it loses energy. According to the law of conservation of

energy, the energy lost by the electron must go somewhere.


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It works the other way, too. If a photon strikes an atom, the atom can

absorb the photon and its energy if (and only if) the photon's energy

is exactly equal to the difference between two orbital energies. In

this case, an electron uses the photon's energy to jump from the

smaller orbit up to the larger orbit. This is called a quantum jump.

The electron falls down to a lower orbit

and the atom loses energy. A photon

carries away the energy lost by the atom.

A photon is absorbed by the atom, which gains

the photons energy. The electron uses this

energy to jump up to a higher orbit.


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The Schrdinger equation


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The Schrdinger equation


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Wavefunction

A wavefunction is a mathematical function obtained by solvingthe Schrodinger equation and which contains all the dynamical

information about the system


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Wave-Particle Duality


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Energi

kinetik:

Work function


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The Uncertainty Principle

The Heisenberg uncertainty principle states that it is impossible to specify

simultaneously, with arbitrary precision, both the momentum and the position of

a particle


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The Postulates of Quantum Mechanics


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Applications of Quantum Mechanics

Transistors and semiconductors


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Scanning tunneling microscope


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Fluorescent lights

Neon gases gives red coloured light while Krypton gives white

coloured lights. This is the working principle of colourful

fluorescent lights on the streets.


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Lasers

Light Amplification by

Stimulated Emission of

Radiation


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Magnetic Resonance Imaging (MRI)

MRI works because of manipulation of a

quantum-mechanical phenomenon called particle

spin inside the human body. The magnetic fields

produced by the atomic nuclei in the human body

are detected and then displayed as an image.


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Electron microscopy


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Fourier Transform Infra Red (FTIR)


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Spectrometry

Emission


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Absorption


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QUESTIONS?

Terima kasih | Merci beaucoup

1. physics; classic vs quantum

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