Chapter 12: X-rays

Production of X-Rays

X- Rays Spectrum

Bragg's Law

Phenomenon

2dsinθ=nλ

Properties of X-Rays

High penetrating power

Short wavelength, High frequency

Cause photoelectric emmission

Can cause Zinc Sulphide to fluorescence

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When fast-moving electrons slam into the metallic object it loses their speed the kinetic energy is low and then transforms into X-rays.

Reqiurements to produce X-Rays

Source of electrons

Accelerating the electrons at high speeds

A target material to receive the impact of the elelctrons

Procedure

  • Electrons are emitted when the filament(cathode) is hot
  • When the high voltage d.c. supply connected, electron collides the target(anode) at high speed.
  • The high-speed electron collides the metal target(anode), X-Rays produced
  • Less than 1% of the total energy of the colliding electrons is converted into X-rays, others will be converted into heat energy

Type

Characteristics line spectrum

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Energy of X-Rays

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\[\textrm{Discover largest order, }n<=\frac{2d}{\lambda}\]

\[E_{max}=K=eV=\frac{1}{2}mv^2=hf_{max}=\frac{hc}{λ_{min}}\]

From Graph

Relation

  • Area under the graph is equal to the total intensity of X-rays
  • These peaks are characteristic line spectrum.
  • Intensity of X-rays ↑, Number of electrons hitting the target ↑
  • As more heat energy, △T affected
  • Voltage ↑, Energy of electrons ↑, More energy available for X-rays production

Continuous spectrum

  • When the bombarding electron enters the metal target atom, it knocked out the K-shell electron and leave a space.
  • Shell K more stable, the electron at higher energy level will fill the space ,this form x-ray
  • The electron usually has more than one encounter before it loses all its energy.
  • Different electrons lose different amounts of energy, so a continuous spectrum covering a range of wavelength is obtained.