Quantum physics general

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Slide 10

The photoelectric effect

1905 - Einstein

The emission of electrons from a surface (usually metallic) upon exposure to, and absorption of, electromagnetic radiation.

The photoelectric effect was explained mathematically by Einstein who extended the work on QUANTA as developed by Planck.

Slide 11

Millikan’s oil drop experiment

1909 - Robert Millikan

This experiment determined the magnitude of the electronic charge, and that it was QUANTISED.

This value is approximately

Note: An electron volt (eV) is the amount of energy it takes to accelerate one electron through a potential of one volt. Thus, 1eV

Slide 12

De broglie wavelength

Prince Louis de Broglie - 1932

De Broglie discovered that all particles with momentum have an associated wavelength.

What is the wavelength of a human being, assuming he/she weighs 70 kg, and is running at 25 m/s?

Slide 13

Nuclear atom structures

1898 - Thomson

Slide 14

1911 -Rutherford

Slide 15

1913 - Rutherford/Bohr

Slide 16

Atomic Line Spectra

Slide 17

General expression:

Lyman: n>1 (ultraviolet)

Balmer: n>2 (visible)

Paschen: n>3 (infrared)

Brackett: n>4 (infrared)

Pfund: n>5 (infrared)

Slide 18

Summary of important equations

Energy and frequency:

The photoelectric effect:

De Broglie wavelength:

Angular frequency:

Slide 19

Equations of interest (non-examinable!)

Planck’s constant:

Wave vector:

Schroedinger:

Slide 20

Richard Feynman 1918-1988

Anyone who has not been shocked by quantum physics has not understood it.

The word 'quantum' refers to this peculiar aspect of nature that goes against common sense.

Slide 21

Groucho Marx 1890-1977

Very interesting theory - it makes no sense at all!

Slide 22

Quantum theory