Home
Class 12
PHYSICS
Show that a moving electron cannot spont...

Show that a moving electron cannot spontaneously change into an x-ray photon in free space. A third body (atom or nucleus) must be present. Why is it needed?

Text Solution

Verified by Experts

to conserve momentum
Promotional Banner

Topper's Solved these Questions

  • ALL ABOUT ATOMS

    RESNICK AND HALLIDAY|Exercise PRACTICE QUESTIONS (SINGLE CORRECT CHOICE TYPE)|57 Videos

  • ALL ABOUT ATOMS

    RESNICK AND HALLIDAY|Exercise PRACTICE QUESTIONS (MORE THAN ONE CORRECT CHOICE TYPE)|4 Videos

  • ALL ABOUT ATOMS

    RESNICK AND HALLIDAY|Exercise CHECKPOINT|1 Videos

  • CAPACITANCE

    RESNICK AND HALLIDAY|Exercise PRACTICE QUESTION (INTEGER TYPE)|3 Videos

Similar Questions

Explore conceptually related problems

(i) Show that a free electron at rest cannot absorb a photon and thereby acquire kinetic energy equal to the energy of the photon. Would the conclusion change if the free electron was moving with a constant velocity ? (ii) If the absorption of a photon by a free electron is ruled out as proved in (i) above, how does photoelectric emission take place at all ?

Rutherford's alpha -particle scattering experiment showed that (i) electrons have negative charge. (ii) the mass and positive charge of the atom is concentrated in the nucleus. (iii) neutron exists in the nucleus. (iv) most of the space in atom is empty. Which of the above statements are correct ?

When an electron moving at a high speed strikes a metal surface, which of the following are possible? (i) The entire energy of the electron may be converted into an X-ray photon (ii) Any fraction of energy of the electron may be converted into an X-ray photon (iii) The entire energy of the electron may get converted to heat (iv) The electron may undergo elastic collision with the metal surface

What factor determines whether the crystal field in an octahedral complex is to be regarded as strong or weak? How many d-electrons must be present in orbitals of the central atom atom for there to be an abrupt change in crystal field stabilisation energy strong and weak fields gt

Dependence of Spontaneity on Temperature: For a process to be spontaneous , at constant temperature and pressure , there must be decrease in free energy of the system in the direction of the process , i.e. DeltaG_(P.T) lt 0. DeltaG_(P.T) =0 implies the equilibrium condition and DeltaG_(P.T) gt 0 corresponds to non- spontaneity. Gibbs- Helmholtz equation relates the free energy change to the enthalpy and entropy changes of the process as : " "DeltaG_(P.T) = DeltaH-TDeltaS" ""..."(1) The magnitude of DeltaH does not change much with the change in temperature but the entropy factor TDeltaS change appreciably . Thus, spontaneity of a process depends very much on temperature. For endothermic process, both DeltaH and DeltaS are positive . The energy factor, the first factor of equation, opposes the spontaneity whereas entorpy factor favours it. At low temperature the favourable factor TDeltaS will be small and may be less than DeltaH, DeltaG will have positive value indicated the nonspontaneity of the process. On raising temperature , the factor TDeltaS Increases appreciably and when it exceeds DeltaH, DeltaG would become negative and the process would be spontaneous . For an expthermic process, both DeltaH and DeltaS would be negative . In this case the first factor of eq.1 favours the spontaneity whereas the second factor opposes it. At high temperature , when T DeltaS gt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity fo the process . However , on decreasing temperature , the factor , TDeltaS decreases rapidly and when TDeltaS lt DeltaH, DeltaG becomes negative and the process occurs spontaneously. Thus , an exothermic process may be spontaneous at low temperature and non-spontaneous at high temperature. The enthalpy change for a certain rection at 300 K is -15.0 K cal mol^(-1) . The entropy change under these conditions is -7.2 cal K^(-1)mol^(-1) . The free energy change for the reaction and its spontaneous/ non-spontaneous character will be

The energy-level scheme for the hypothetical one electron element Bansalium is shown in figure. The potential energy is taken to be zero for an electron at an infinite distance from the nucleus. If a Bansalium atom is in ground state, which of the following photons cannot excite the atom to a higher state?

In an ordianary atom, as a first approximation, the motion of the nucleus can be ignored. In a positronium atom a positronreplaces the proton of hydrogen atom. The electron and positron masses are equal and , therefore , the motion of the positron cannot be ignored. One must consider the motion of both electron and positron about their center of mass. A detailed analyasis shows that formulae of Bohr's model apply to positronium atom provided that we replace m_(e) by what is known reduced mass is m_(e)//2 . If the Rydberg constant for hydrogen atom is R , then the Rydberg constant for positronium atom is

In an ordianary atom, as a first approximation, the motion of the nucleus can be ignored. In a positronium atom a positronreplaces the proton of hydrogen atom. The electron and positron masses are equal and , therefore , the motion of the positron cannot be ignored. One must consider the motion of both electron and positron about their center of mass. A detailed analyasis shows that formulae of Bohr's model apply to positronium atom provided that we replace m_(e) by what is known reduced mass is m_(e)//2 . The orbital radius of the first excited level of postronium atom is

An X-ray tube operates at 40 kV. Suppose the electron converts 70% of its energy into a photon at each collision. Find the lowest three wavelengths emitted from the tube. Neglect the energy imparted to the atom with which the electron collides.

RESNICK AND HALLIDAY-ALL ABOUT ATOMS -PROBLEMS
  1. The x rays shown are produced when 35.0 ke V electrons strike a molybd...

    Text Solution

    |

  2. (a) From Eq. what is the ratio of the photon energies due to K(alpha) ...

    Text Solution

    |

  3. Show that a moving electron cannot spontaneously change into an x-ray ...

    Text Solution

    |

  4. A population inversion for two energy levels is often described by ass...

    Text Solution

    |

  5. Two of the three electrons in a lithium atom have quantum numbers (n, ...

    Text Solution

    |

  6. A pulsed laser emits light at a wavelength of 694.4 nm. The pulse dura...

    Text Solution

    |

  7. From Fig, calculate approximately the energy different E(L)-E(M) for m...

    Text Solution

    |

  8. For a helium atom in its ground state, what are quantum numbers (n,l,m...

    Text Solution

    |

  9. A hypothetical atom has two energy levels, with a transition wavelengt...

    Text Solution

    |

  10. A laser emits at 424 nm in a single pulse that lasts 0.500mus. The pow...

    Text Solution

    |

  11. X rays are produced in an x-ray tube by electrons accelerated through ...

    Text Solution

    |

  12. Assume that lasers are available whose wavelengths can be precisely ''...

    Text Solution

    |

  13. A certain gas laser can emit light at wavelength 550 nm, which involve...

    Text Solution

    |

  14. How many electron states are there in the following shells: (a) n=4,...

    Text Solution

    |

  15. The active volume of a laser constructed of the semiconductor GaAIAs i...

    Text Solution

    |

  16. In the subshell l=4, (a) what is the greatest (most positive) m(l) val...

    Text Solution

    |

  17. A material whose K -absorption edge is 0.2 Å is irradiated by X-ray of...

    Text Solution

    |

  18. The wavelength of the K(alpha) line from iron is 193 pm. What is the e...

    Text Solution

    |

  19. An electron in a multielectron atom has m(f)=+4. For this electron, wh...

    Text Solution

    |

  20. A hypothetical atom has energy levels uniformly separated by 1.2 eV. A...

    Text Solution

    |