Advertisements
Advertisements
प्रश्न
Define the term "Threshold frequency", in the context of photoelectric emission.
Advertisements
उत्तर
For a given Photosensitive material, there is a certain minimum cut off frequency at which Photoelectric emission is possible is called Threshold frequency, i.e. At this frequency just emission of photoelectrons happens without giving them any kind of additional energy. Higher the work function of the material, greater is the Threshold frequency. See the figure below of two different metals having different Threshold Frequency.
APPEARS IN
संबंधित प्रश्न
Find the (a) maximum frequency and (b) minimum wavelength of X-rays produced by 30 kV electrons.
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?
How does one explain the emission of electrons from a photosensitive surface with the help of Einstein's photoelectric equation?
The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the place current decrease, increase or remain the same?
Why do metals have a large number of free electrons?
What do you mean by electron emission? Explain briefly various methods of electron emission.
Photoelectric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light (ν1 > ν2). If the maximum value of kinetic energy of the photoelectrons emitted in the two cases are in the ration 1 : n then the threshold frequency of the metallic surface is ______.
Consider Figure for photoemission.
How would you reconcile with momentum conservation? Note light (photons) have momentum in a different direction than the emitted electrons.
Give an example each of a metal from which photoelectric emission takes place when irradiated by
- UV light
- visible light.
