Name: Photoelectric Effect: Threshold Frequency & Wavelength
Uploaded: 2019-07-19
Duration: 5 min 56 s
Description: This video sheds light on the concepts of threshold frequency, threshold wavelength of metal, and their relation with the work function. Watch the video to l...

Question

Draw a neat diagram of a Coolidge tube and describe how X rays are produced by it. On what factor does the minimum wavelength of produced X-rays depends. State the similarity and differences between X-rays and visible light.

Accepted Answer

The characteristic features of the Coolidge tube are its high vacuum and its use of a heated filament as the source of electrons. There is so little gas inside the tube that it is not involved in the production of x-rays, unlike the situation with cold cathode gas discharge tubes. The operation of the Coolidge tube is as follows. As the cathode filament is heated, it emits electrons. The hotter the filament gets, the greater the emission of electrons. These electrons are accelerated towards the positively charged anode and when the electrons strike the anode, they change direction and emit bremsstrahlung, i.e., x-rays with a continuous range of energies. The maximum energy of the x-rays is the same as the kinetic energy of the electrons striking the anode. In addition to the x-rays produced at the focal spot of the anode, some undesirable x-rays (stray radiation) are produced by electrons striking other tube components.

Difference between X-rays and Visible Light:- X-rays are high energy electromagnetic waves, but visible light is medium energy electromagnetic waves. The visible spectrum is very narrow compared to the X-ray spectrum. X-rays can penetrate the human body, but visible light is not capable of doing that.

Draw a neat diagram of a Coolidge tube and describe how X rays are produced by it. On what factor does the minimum wavelength of produced X-rays depends. State the similarity and differences between X-rays and visible light.

Important Questions on Photoelectric Emission and Production and Properties of X-Rays

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