The Experimental Basis of Quantum Theory. Thornton and Rex, Ch. 3

Transcription

1 The Experimental Basis of Quantum Theory Thornton and Rex, Ch. 3

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6 Q uick uiz When an object gets hot, it radiates energy. As the temperature increases, the properties of this radiation are:- (A) (B) (C) (D) (E) frequency remains constant, wavelength increases frequency decreases, wavelength increases frequency increases, wavelength decreases frequency increases, wavelength remains constant both frequency and wavelength remain constant

7 Q uick uiz When an object gets hot, it radiates energy. As the temperature increases, the properties of this radiation are:- (A) (B) (C) (D) (E) frequency remains constant, wavelength increases frequency decreases, wavelength increases frequency increases, wavelength decreases frequency increases, wavelength remains constant both frequency and wavelength remain constant

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10 Digression on Phillip Lenard "The most important example of the dangerous influence of Jewish circles on the study of nature has been provided by Herr Einstein with his mathematically botchedup theories consisting of some ancient knowledge and a few arbitrary additions. This theory now falls to pieces, as is the fate of all products that are estranged from nature. Even scientists who have otherwise done solid work cannot escape the reproach that they allowed the relativity theory to get a foothold in Germany, because they did not see, or did not wish to see, how wrong it is, outside the field of science also, to regard this Jew as a good German. Phillip Lenard

11 Digression on Phillip Lenard "The most important example of the dangerous influence of Jewish circles on the study of nature has been provided by Herr Einstein with his mathematically botchedup theories consisting of some ancient knowledge and a few arbitrary additions. This theory now falls to pieces, as is the fate of all products that are estranged from nature. Even scientists who have otherwise done solid work cannot escape the reproach that they allowed the relativity theory to get a foothold in Germany, because they did not see, or did not wish to see, how wrong it is, outside the field of science also, to regard this Jew as a good German. Phillip Lenard "Great spirits have always encountered violent opposition from mediocre minds. Albert Einstein

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13 Q uick uiz In the photoelectric effect, as the wavelength of the incident light increases:- (A) (B) (C) (D) (E) the intensity of the photoelectrons increases the energy of the photoelectrons increases the work function of the metal surface increases the energy of the photoelectrons decreases the work function of the metal surface decreases

14 Q uick uiz In the photoelectric effect, as the wavelength of the incident light increases:- (A) (B) (C) (D) (E) the intensity of the photoelectrons increases the energy of the photoelectrons increases the work function of the metal surface increases the energy of the photoelectrons decreases the work function of the metal surface decreases

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19 Q uick uiz What is the approximate wavelength of Spartan Green light? (A) (B) (C) (D) (E) 210 nm 310 nm 410 nm 510 nm 610 nm

20 Q uick uiz What is the approximate wavelength of Spartan Green light? (A) (B) (C) (D) (E) 210 nm 310 nm 410 nm 510 nm 610 nm

21 X Ray Spectra Electrons bombarding a high-z target Incident electron KE: Ko = evo Wavelength distribution of X-Rays Lines : knock atomic e s out of metal anode (see spectral lines in a few slides)

22 Smooth continuum: Deceleration of incident e s in anode radiate X rays Distribution of energies: bremsstrahlung Xrays: E = hν = hc/λ For a given incident KE, largest los s = smallest λ λ min = hc/ko or Ko = 1240/ λ min (ev nm) Example: cutoff wavelength of.035 nm corresponds to acceleration voltage V of Ko = ev = 1240 ev nm /.035 nm, so V = 3550 Volts. Note: hc is very flexible: coordinated change of units in energy and wavelength hc = 1240 ev nm nano = 1240 kev pm pico = 1240 MeV fm femto

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28 Q uick uiz A photon of energy, E = 200 kev is reflected at θ = 180 o from an electron. If the energy of the reflected photon is E = 112 kev, what is the kinetic energy of the recoil electron? (A) (B) (C) (D) (E) 56 kev 88 kev 112 kev 200 kev 312 kev

29 Q uick uiz A photon of energy, E = 200 kev is reflected at θ = 180 o from an electron. If the energy of the reflected photon is E = 112 kev, what is the kinetic energy of the recoil electron? (A) (B) (C) (D) (E) 56 kev 88 kev 112 kev 200 kev 312 kev

30 Q uick uiz A photon of wavelength, λ = 6.2E-3 nm (=6.2 pm) is reflected at θ = 180 o from an electron. If the wavelength of the reflected photon is λ = 11.06E-3 nm (=11.06 pm), what is the kinetic energy of the recoil electron? (A) (B) (C) (D) (E) 56 kev 88 kev 112 kev 200 kev 312 kev

31 Q uick uiz A photon of wavelength, λ = 6.2E-3 nm (=6.2 pm) is reflected at θ = 180 o from an electron. If the wavelength of the reflected photon is λ = 11.06E-3 nm (=11.06 pm), what is the kinetic energy of the recoil electron? (A) (B) (C) (D) (E) 56 kev 88 kev 112 kev 200 kev 312 kev