Advertisements
Advertisements
प्रश्न
Find the (a) maximum frequency and (b) minimum wavelength of X-rays produced by 30 kV electrons.
Advertisements
उत्तर
Potential of the electrons, V = 30 kV = 3 × 104 V
Hence, energy of the electrons, E = 3 × 104 eV
Where,
e = Charge on an electron = 1.6 × 10−19 C
(a) Maximum frequency produced by the X-rays = v
The energy of the electrons is given by the relation.
E = hv
Where,
h = Planck’s constant = 6.626 × 10−34 Js
∴ v = `E/h`
= `(1.6 xx 10^(-19) xx 3 xx 10^4)/(6.626 xx 10^(-34))`
= 7.24 × 1018 Hz
Hence, the maximum frequency of X-rays produced is 7.24 × 1018 Hz.
(b) The minimum wavelength produced by the X-rays is given as:
`lambda = c/v`
= `(3 xx 10^8)/(7.24 xx 10^18)`
= 4.14 × 10−11 m
= 0.0414 nm
Hence, the minimum wavelength of X-rays produced is 0.0414 nm.
संबंधित प्रश्न
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?
How does one explain the emission of electrons from a photosensitive surface with the help of Einstein's photoelectric equation?
Answer the following question.
Define the term "Threshold frequency", in the context of photoelectric emission.
The work function of aluminum is 4⋅2 eV. If two photons each of energy 2⋅5 eV are incident on its surface, will the emission of electrons take place? Justify your answer.
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 ______.
Give an example each of a metal from which photoelectric emission takes place when irradiated by
- UV light
- visible light.
Name the factors on which photoelectric emission from a surface depends.
In the boundary-wall analogy, what is the minimum push needed for a free electron to jump over the wall and come out?
What is electron emission?
What is the work function (\[\phi_0\]) of a metal?
Which particles at the surface hold free electrons inside the metal?
Which are the three main ways electrons can be emitted from a metal surface?
What supplies energy to electrons in thermionic emission?
Which is an example associated with photoelectric emission?
