Description

Wave Molecule Duality. Quantum Material science Lesson 3. Today's Targets. Clarify what is implied by wave-molecule duality. Depict the primary purposes of de Broglie's speculation that matter particles additionally have a wave-like nature. State and utilize the mathematical statement ? = h/p = h/mv

Transcripts

Wave Particle Duality Quantum Physics Lesson 3

Today\'s Objectives Explain what is implied by wave-molecule duality. Depict the principle purposes of de Broglie\'s theory that matter particles likewise have a wave-like nature. State and utilize the condition λ = h/p = h/mv Describe prove for de Broglie\'s speculation.

Wave molecule duality We have seen… … .. Photons : Quanta (particles) of light Electrons: Being diffracted. A property of waves

Prince Louis de Broglie 1892-1987 Electrons ought not be viewed as just as particles, but rather that recurrence must be relegated to them too. (1929, Nobel Prize Speech)

De Broglie (1924) Suggested that particles, for example, electrons may demonstrate wave properties. He summised that the de Broglie wavelength , λ was given by: m = mass v = speed of the molecule

Note that:- This is a matter wave condition not electromagnetic wave The de Broglie wavelength can be modified by changing the speed of the molecule.

In words...

The diffraction tube

Summary of Experiment Beam of electrons coordinated at a thin metal thwart. Lines of iotas cause the electron bar to be diffracted in specific headings as it were. We watch rings because of electrons being diffracted by a similar sum from grains of various introductions, at a similar point to the occurrence shaft.

What we ought to see

Electron diffraction 1927: Davisson & Gerner affirmed this expectation with trials utilizing electron bars. They really utilized a nickel focus rather than a carbon one (we utilized) The wavelength they gauged concurred with de Broglie There is a connection between the quickening voltage V and the k.e . of the particles

Diffraction impacts have been appeared for Hydrogen iotas Helium molecules Neutrons Neutron diffraction is a phenomenal method for contemplating gem structures.

De Broglie Wavelength In 1932, De Broglie found that all particles with energy have a related wavelength. What is the wavelength of an individual, expecting he/she measures 70 kg, and is running at 25 m/s?

Practice Questions 1.Find the wavelength of an electron of mass 9.00 × 10 - 31 kg moving at 3.00 × 10 7 m s - 1 2. Discover the wavelength of a cricket bundle of mass 0.15 kg moving at 30 m s - 1 . 3. It is additionally alluring to have the capacity to ascertain the wavelength related with an electron when the quickening voltage is known. There are 3 stages in the estimation. Compute the wavelength of an electron quickened through a potential contrast of 10 kV.

Step 1: Kinetic vitality E K = eV = 1.6 × 10 - 19 × 10000 = 1.6 × 10 - 15 J Step 2: E K = ½ mv 2 = ½m ( mv ) 2 = p 2/2m, so energy p = √2m E k = √2 × 9.1 × 10 - 31 × 1.6 × 10 - 15 = 5.4 × 10 - 23 kg m s - 1 Step 3: Wavelength λ = h/p = 6.63 × 10 - 34/5.4 × 10 - 23 = 1.2 × 10 - 11 m = 0.012 nm.

Slit separating, d Wavelength, Distance to screen, L Fringe dividing, x d 2 Laser d 1 L 1 Slits L 2 Screen 1 Screen 2

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