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
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
Energy of X-Rays
\[\textrm{Discover largest order, }n<=\frac{2d}{\lambda}\]
\[E_{max}=K=eV=\frac{1}{2}mv^2=hf_{max}=\frac{hc}{λ_{min}}\]
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.