n a medium of refractive index 𝑛, the wavelength of light 𝜆0 is related to its frequency 𝑓0 via the relation𝜆0 = 𝑐/(𝑛𝑓0) , where 𝑐 is the speed of light in vacuum. Fig. 1 is labelled with variables of relevance,including input photon frequency 𝑓, outgoing photon angle 𝜃, outgoing photon frequency 𝑓′, outgoingelectron angle 𝜙, outgoing electron energy 𝐸 and outgoing electron momentum 𝒑. In this problem, themomenta of all particles, before and after, lie entirely in the plane of the paper.1. Write the energy conservation equation and the momentum conservation equations for Comptonscattering for incident and outgoing photons in a medium of refractive index 𝑛. Explain youranswer in detail
Question
n a medium of refractive index 𝑛, the wavelength of light 𝜆0 is related to its frequency 𝑓0 via the relation𝜆0 = 𝑐/(𝑛𝑓0) , where 𝑐 is the speed of light in vacuum. Fig. 1 is labelled with variables of relevance,including input photon frequency 𝑓, outgoing photon angle 𝜃, outgoing photon frequency 𝑓′, outgoingelectron angle 𝜙, outgoing electron energy 𝐸 and outgoing electron momentum 𝒑. In this problem, themomenta of all particles, before and after, lie entirely in the plane of the paper.1. Write the energy conservation equation and the momentum conservation equations for Comptonscattering for incident and outgoing photons in a medium of refractive index 𝑛. Explain youranswer in detail
Solution
Compton scattering is a phenomenon in which a photon scatters off a charged particle, usually an electron. In this process, the photon transfers some of its energy to the electron, resulting in a decrease in the photon's energy (or equivalently, an increase in its wavelength) and an increase in the electron's kinetic energy.
- Energy Conservation Equation:
The energy conservation equation for Compton scattering in a medium of refractive index n can be written as:
hf + mc^2 = h*f' + E
where:
- h is Planck's constant,
- f is the frequency of the incident photon,
- m is the electron rest mass,
- c is the speed of light in vacuum,
- f' is the frequency of the scattered photon, and
- E is the kinetic energy of the scattered electron.
This equation states that the total energy before the scattering (the energy of the photon plus the rest energy of the electron) is equal to the total energy after the scattering (the energy of the scattered photon plus the kinetic energy of the scattered electron).
- Momentum Conservation Equations:
The momentum conservation equations for Compton scattering in a medium of refractive index n can be written as:
p = hf/c + pcos(φ)
p' = hf'/c + pcos(θ)
where:
- p is the momentum of the incident photon,
- φ is the angle between the incident photon and the scattered electron, and
- θ is the angle between the scattered photon and the scattered electron.
These equations state that the total momentum in the direction of the incident photon before the scattering (the momentum of the photon plus the component of the electron's momentum in that direction) is equal to the total momentum in that direction after the scattering (the momentum of the scattered photon plus the component of the scattered electron's momentum in that direction). Similarly, the total momentum perpendicular to the direction of the incident photon before the scattering is equal to the total momentum in that direction after the scattering.
Similar Questions
10. Choose the incorrect statement(a) The number of photoelectrons emitted is proportional to light intensity(b) The velocity of photoelectrons is proportional to the frequency of light(c) Photoelectric effect is an instantaneous process.(d) Stopping potential is independent of incident frequency.11. Choose the incorrect statement. In the Compton scattering-(a) The increase in wavelength ∆𝜆, is independent of the incident wavelength.(b) Compton wavelength is always a constant quantity.(c) The wavelength increase, ∆𝜆, depends on the scattering angle of the photon(d) The wavelength increase is independent of the scattering angle of a photon.12. The phase speed of matter waves for a relativistic free moving particle in a vacuum is;(a) Equal to the speed of light in a vacuum(b) Less than the speed of light in a vacuum(c) More than the speed of light in a vacuum(d) Equal to half the speed of light in a vacuum
Solve the equations to obtain the outgoing photon frequency 𝑓′ in the following form:𝑓′ = (−𝐵 ± √𝐵2 − 4𝐴𝐶)2𝐴where you are to determine the unknowns 𝐴, 𝐵 and 𝐶 in terms of 𝑓, 𝑐, 𝑛, 𝜃, and electron restmass 𝑚. You may use the fact that for general (relativistic) electrons, the dispersion relation is𝐸 = √𝑝2𝑐2 + 𝑚2𝑐4
Compton shift depends ona.angle of recoil of electronb.wavelength of radiationc.angle of scattering of photon
Under what condition Compton shift in wavelength is maximum? Elaborate your answer.
Which of the following phenomena cannot be explained by the wave theory of light?(a) Interference(b) Diffraction(c) Reflection(d) None of the above2. In the Compton effect, the change in wavelength of a scattered photon depends on(a) Wavelength of an incident photon(b) Intensity of Incident Radiation(c) Scattering Angle(d) All of the above3. Calculate the de-Broglie wavelength (in Å), if an electron is accelerated from rest througha potential different 𝑉 = 50 𝑉.(a) 2.4 Å (b) 9.2 Å(c) 1.73 Å (d) 5.7 Å4. The operator for momentum is(a) ℏ ∇ଶ (b) ∇ଶ(c) ℏ ∇ (d) ି ℏ ∇5. If a proton and an alpha-particle are accelerated through the same potential difference,then the ratio of their de-Broglie wavelengths will be(a) √8: 1 (b) 1: √8(c) √2: 1 (d) 1: √26. A proton and an alpha-particle are confined in 1-D potential boxes of lengths L and L/2respectively. If Ep and Eα are their ground state energies, then(a) 𝐸ఈ = 𝐸 2⁄ (b) 𝐸ఈ = 2𝐸(c) 𝐸ఈ = 𝐸 (d) 𝐸ఈ = ඥ𝐸7. Which of the following phenomena shows the wave nature of an electron?(a) Compton effect (b) Diffraction of electron by crystal(c) Photoelectric effect (d) Thermionic emission8. For a dispersive medium(a) Phase velocity is equal to the group velocity.(b) Phase velocity is not equal to the group velocity.(c) Both (a) and (b) are trueDepartment of physics Tutorial: unit 36(d) None of these are true9. Schrodinger wave equation is applicable to(a) Relativistic motion only(b) Non-relativistic motion only(c) Neither for relativistic motion nor for non-relativistic motion(d) Both relativistic motion and non-relativistic motion10. Choose the incorrect statement(a) The number of photoelectrons emitted is proportional to light intensity(b) The velocity of photoelectrons is proportional to the frequency of light(c) Photoelectric effect is an instantaneous process.(d) Stopping potential is independent of incident frequency.11. Choose the incorrect statement. In the Compton scattering-(a) The increase in wavelength ∆𝜆, is independent of the incident wavelength.(b) Compton wavelength is always a constant quantity.(c) The wavelength increase, ∆𝜆, depends on the scattering angle of the photon(d) The wavelength increase is independent of the scattering angle of a photon.12. The phase speed of matter waves for a relativistic free moving particle in a vacuum is;(a) Equal to the speed of light in a vacuum(b) Less than the speed of light in a vacuum(c) More than the speed of light in a vacuum(d) Equal to half the speed of light in a vacuum13. A moving particle is associated with a wave packet or group of waves. The groupvelocity is equal to;(a) Velocity of light(b) Velocity of sound(c) Velocity of particle(d) Square of the particle velocity14. The uncertainty principle states that the error in measurement is due to;(a) Dual nature of light(b) Due to the small size of particles(c) Due to the large size of particles(d) Due to the error in measuring instruments15. Uncertainty relation cannot hold for the following pairs;(a) Position and momentum(b) Energy and time(c) Linear momentum and angleDepartment of physics Tutorial: unit 37(d) Angular momentum and angle16. The duration of a radar pulse is 10-6 sec. The uncertainty in its energy will be;(a) 1.05 × 10ିଵସ J(b) 1.05 × 10ି ଶ J(c) 1.05 × 10ିଶ଼ J(d) 1.05 × 10ି ଷ J17. Compton effect supports;(a) Wave nature of radiation(b) Particle nature of radiation(c) Both particle and wave nature of radiation(d) None of these18. An X-ray photon is found to have its wavelength doubled on being scattered through 90⁰.The wavelength is;(a) 0.024 𝑚(b) 0.240 𝑚(c) 0.042 𝑚(d) 0.024 Å19. X-rays of wavelength 1 Å are scattered at such an angle that the recoil electron hasmaximum kinetic energy. The wavelength of scattered rays is;(a) 0.048 Å(b) 0.480 Å(c) 2.048 Å(d) 1.048 Å20. The equation of motion of matter waves is derived by;(a) Heisenberg(b) de-Broglie(c) Bohr(d) Schrodinger21. 𝑆𝑖𝑛 2𝑥 is an eigenfunction of the operator;(a) − ௗௗ௫ b) + ௗௗ௫(c) − ௗమௗ௫మ (d) + ௗమௗ௫మ22. The allowed eigenfunction must be;(a) Finite only(b) Continuous only(c) Single-valued only(d) All of the threeDepartment of physics Tutorial: unit 3823. Schrodinger wave equation is(a) An equation of motion for an electron moving at non-relativistic velocities(b) An equation of motion for proton accelerated at some potential difference V(c) An equation of motion of a de-Broglie wave(d) None of these24. Which of the following has more precise information about the position of a particle?(a) Energy(b) Wave-function(c) Probability(d) Expectation value25. According to wave mechanics, a free particle can possess;(a) Discrete energies(b) Continuous energies(c) Only a single values energy(d) None of these26. A particle moving in an infinitely deep potential can have energies which are multiple of;(a) 𝑛ଶ(b) 𝑛(c) 1.5𝑛(d) 𝑛ଷTUTORIAL SHEET1. Find the maximum wavelength that can liberate an electron from potassium. The work function
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