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Difficulty: EasyX-rays: Production, Properties, and Applications

In an X-ray tube, which of the following adjustments will increase the penetrating power (hardness) of the emitted X-rays?

  1. Increasing the accelerating potential difference between the anode and cathodeAnswer
  2. B
    Increasing the current passing through the filament heater
  3. C
    Decreasing the potential difference across the X-ray tube
  4. D
    Increasing the surface area of the target anode

Answer

Increasing the accelerating potential difference between the anode and cathode increases the penetrating power of X-rays.
Increasing the accelerating potential difference between the anode and cathode increases the energy transferred to the colliding electrons. According to the Duane-Hunt law (eV=hfmaxe V = h f_{\text{max}}), higher potential difference leads to higher frequency X-ray photons, which increases their penetrating power (hardness).

Step-by-Step Solution

1
Identify the factor controlling electron kinetic energy
Maximum kinetic energy of electrons is Emax=eVE_{\text{max}} = e V, directly proportional to the tube voltage VV.
Electrons gain energy from the electric field established by the potential difference.
2
Relate electron energy to X-ray photon energy and penetrating power
Higher kinetic energy produces X-ray photons of higher maximum frequency (fmax=eVhf_{\text{max}} = \frac{e V}{h}) and shorter minimum wavelength (hard X-rays).
Hard X-rays with higher frequencies have greater energy and higher penetrating power.

Key Concept

X-ray Hardness vs. Intensity Control
Estimated Time:45s
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Topics

X-rays: Production, Properties, and Applications

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