Advertisements
Advertisements
प्रश्न
Consider a beam of electrons (each electron with energy E0) incident on a metal surface kept in an evacuated chamber. Then ______.
पर्याय
no electrons will be emitted as only photons can emit electrons.
electrons can be emitted but all with an energy, E0.
electrons can be emitted with any energy, with a maximum of E0 – φ (φ is the work function).
electrons can be emitted with any energy, with a maximum of E0.
उत्तर
Consider a beam of electrons (each electron with energy E0) incident on a metal surface kept in an evacuated chamber. Then electrons can be emitted with any energy, with a maximum of E0.
Explanation:
If a beam of electrons of having energy E0 is incident on a metal surface kept in an evacuated chamber.
The electrons can be emitted with maximum energy E0 (due to elastic collision) and With any energy less than E0, when part of the incident energy of electron is used in liberating the electrons from the surface of metal.
APPEARS IN
संबंधित प्रश्न
Draw a neat labelled diagram for Davisson and Germer experiment, for diffraction of electron wave.
An electron microscope uses electrons accelerated by a voltage of 50 kV. Determine the de-Broglie wavelength associated with the electrons. Taking other factors, such as numerical aperture etc. to be same, how does the resolving power of an electron microscope compare with that of an optical microscope which used yellow light?
The wavelength of a probe is roughly a measure of the size of a structure that it can probe in some detail. The quark structure of protons and neutrons appears at the minute length-scale of 10−15 m or less. This structure was first probed in early 1970’s using high energy electron beams produced by a linear accelerator at Stanford, USA. Guess what might have been the order of energy of these electron beams. (Rest mass energy of electron = 0.511 MeV.)
Calculate n(T)/n(1000 K) for tungsten emitter at T = 300 K, 2000 K and 3000 K, where n(T) represents the number of thermions emitted per second by the surface at temperature T. Work function of tungsten is 4.52 eV.
A tungsten cathode and a thoriated-tungsten cathode have the same geometric dimensions and are operated at the same temperature. The thoriated-tungsten cathode gives 5000 times more current than the other cathode. The constant A in the Richardson−Dushman equation is 60 × 104 Am −2 K−2 for pure tungsten and 3.0 × 104 Am −2 k−2 for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV. Find the operating temperature.
If the temperature of a tungsten filament is raised from 2000 K to 2010 K, by what factor does the emission current change? Work function of tungsten is 4.5 eV.
What conclusion can be drawn from Davisson and Germer’s experiment ?
In Davisson and Germer experiment maximum intensity is observed at ______.
Consider figure in the NCERT textbook of physics for Class XII. Suppose the voltage applied to A is increased. The diffracted beam will have the maximum at a value of θ that ______.
Match List -I (Fundamental Experiment) with List -II (its conclusion) and select the correct option from the choices given below the list:
| List -I | List -II | ||
| A. | Franck- Hertz experiment |
(i) | Particle nature of light |
| B. | Photo-electric experiment |
(ii) | Discrete energy levels of atom |
| C. | Davisson Germer experiment |
(iii) | Wave nature of electron |
| (iv) | Structure of atom |
