Advertisements
Advertisements
प्रश्न
The work function of the following metals is given : Na 2.75 ev, K = 2.3 eV, Mo = 4.17 eV and Ni = 5.15 eV. Which of these metals will not cause photoelectric emission for radiation of wavelength 3300 Å from a laser source placed 1 m away from these metals? What happens if the laser source is brought nearer and placed 50 cm away?
Advertisements
उत्तर
λ=3300 Å =330 nm
Energy possessed by this wave = `(hc)/λ= 1240/330 = 3.76 eV`
As the work function of Mo and Ni is more than the energy in the wave, so in Mo and Ni no photoelectric emission will happen.
If laser source is brought near, no effect will be seen as the energy of the wave will still be same.
APPEARS IN
संबंधित प्रश्न
The work function of caesium metal is 2.14 eV. When light of frequency 6 × 1014 Hz is incident on the metal surface, photoemission of electrons occurs. What is the
- maximum kinetic energy of the emitted electrons,
- Stopping potential, and
- maximum speed of the emitted photoelectrons?
Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e; (–1/3)e]. Why do they not show up in Millikan’s oil-drop experiment?
Why should gases be insulators at ordinary pressures and start conducting at very low pressures?
Would you prefer a material with a high work-function or a low work-function to be used as a cathode in a diode?
The wavelength λe of an electron and λp of a photon of same energy E are related by ______.
Emission of electrons by the absorption of heat energy is called ____________ emission.
Why do metals have a large number of free electrons?
In which case is electron emission from a metal not known?
Name the factors on which photoelectric emission from a surface depends.
The work function of a metal is 2.31 eV. Photoelectric emission occurs when the light of frequency 6.4 × 1014 Hz is incident on the metal surface. Calculate
- the energy of the incident radiation,
- the maximum kinetic energy of the emitted electron and
- the stopping potential of the surface.
