Production of X-rays MCQs With Answer

Production of X-rays MCQs With Answer

X-ray–based techniques such as XRPD (X-ray powder diffraction) and XRF (X-ray fluorescence) are indispensable in Modern Pharmaceutical Analytical Techniques for polymorph identification, crystallinity assessment, and elemental analysis. A clear grasp of how X-rays are generated—inside sealed tubes or rotating-anode generators—helps M. Pharm students optimize beam intensity, wavelength selection, spectral purity, and safety. This quiz focuses on the physics and engineering behind X-ray production: tube voltage and current, bremsstrahlung versus characteristic radiation, target materials, filtration, monochromatization, focal spot geometry, and heat management. Each question is designed to reinforce practical decision-making for pharmaceutical laboratories, from choosing Cu Kα radiation to applying K-edge filters, ensuring you can connect instrument settings to data quality and method robustness.

Q1. Which process in an X-ray tube is primarily responsible for the continuous X-ray spectrum?

• Photoelectric effect in the target
• Bremsstrahlung (braking radiation) from decelerating electrons
• Characteristic transitions from outer shells
• Compton scattering in the tube window

Correct Answer: Bremsstrahlung (braking radiation) from decelerating electrons

Q2. The discrete lines (e.g., Kα, Kβ) in an X-ray spectrum arise due to:

• Electron deceleration in the target’s electric field
• Elastic scattering from the window
• Inner-shell ionization followed by specific electronic transitions
• Bremsstrahlung self-absorption

Correct Answer: Inner-shell ionization followed by specific electronic transitions

Q3. Increasing the tube voltage (kV) primarily results in which effect on the X-ray spectrum?

• Increases maximum photon energy and shifts λmin to shorter wavelength
• Increases the number of photons without changing maximum energy
• Eliminates Kβ lines
• Reduces bremsstrahlung background while preserving line energies

Correct Answer: Increases maximum photon energy and shifts λmin to shorter wavelength

Q4. Which parameter principally controls X-ray photon flux (intensity) without altering the maximum photon energy?

• Tube voltage (kV)
• Tube current (mA)
• Anode angle
• Window material

Correct Answer: Tube current (mA)

Q5. For pharmaceutical XRPD applications, which target is most commonly used due to its suitable wavelength and high intensity?

• Gold (Au) target
• Copper (Cu) target giving Kα ≈ 1.5406 Å
• Silver (Ag) target
• Lead (Pb) target

Correct Answer: Copper (Cu) target giving Kα ≈ 1.5406 Å

Q6. Why is a beryllium window commonly used in X-ray tubes for analytical instruments?

• Its high atomic number maximizes output
• It is inexpensive and easy to machine
• Its low atomic number minimizes X-ray absorption
• It provides intrinsic monochromatization

Correct Answer: Its low atomic number minimizes X-ray absorption

Q7. To generate characteristic K-lines from a target element, the incident electron energy must:

• Be lower than the L-shell binding energy
• Exactly match the Kα photon energy
• Exceed the K-shell binding energy of the target
• Be equal to the Kβ photon energy

Correct Answer: Exceed the K-shell binding energy of the target

Q8. In a Cu-target X-ray tube, which filter is typically used to suppress the Cu Kβ line while transmitting Cu Kα?

• Nickel (Ni) K-edge filter
• Aluminum (Al) filter
• Lead (Pb) filter
• Zirconium (Zr) filter

Correct Answer: Nickel (Ni) K-edge filter

Q9. According to the Duane–Hunt law, the shortest wavelength (λmin) in the spectrum is determined by:

• λmin is independent of tube voltage
• λmin is inversely proportional to the accelerating voltage
• λmin depends only on target material
• λmin is proportional to tube current

Correct Answer: λmin is inversely proportional to the accelerating voltage

Q10. What is the anode heel effect in X-ray tubes?

• An intensity increase toward the anode side due to electron focusing
• Beam hardening caused by external filters
• An intensity reduction toward the anode side due to self-absorption in the target
• Thermal runaway of the filament

Correct Answer: An intensity reduction toward the anode side due to self-absorption in the target

Q11. The line-focus principle allows X-ray tubes to:

• Increase actual focal spot size while reducing heat loading
• Reduce effective focal spot size by tilting the anode without sacrificing heat load
• Eliminate the heel effect at any anode angle
• Generate monochromatic radiation from bremsstrahlung

Correct Answer: Reduce effective focal spot size by tilting the anode without sacrificing heat load

Q12. Compared with sealed tubes, rotating-anode generators provide higher flux primarily because they:

• Use higher-Z windows
• Distribute heat over a larger anode track, allowing greater power loading
• Operate at lower vacuum to enhance emission
• Remove the need for filtration

Correct Answer: Distribute heat over a larger anode track, allowing greater power loading

Q13. Which material is commonly used for the filament in X-ray tubes, and why?

• Tungsten, due to high melting point and efficient thermionic emission
• Copper, due to high thermal conductivity
• Aluminum, to minimize self-absorption
• Lead, to increase electron density

Correct Answer: Tungsten, due to high melting point and efficient thermionic emission

Q14. A high vacuum inside the X-ray tube is essential mainly to:

• Prevent electron scattering by gas molecules
• Increase the number of characteristic lines
• Raise the anode temperature
• Reduce the K-edge of the target

Correct Answer: Prevent electron scattering by gas molecules

Q15. The overall efficiency of X-ray production in a tube is typically:

• High (>50%) and independent of tube voltage
• Moderate (10–20%) and decreases with atomic number
• Very low (<1%) and increases with target Z and tube voltage
• Exactly equal to tube current

Correct Answer: Very low (<1%) and increases with target Z and tube voltage

Q16. Which component placed after the tube most directly produces a narrow spectral band without relying on absorption edges?

• Aluminum attenuator
• Crystal monochromator (e.g., graphite or Ge) using Bragg reflection
• Lead collimator
• Beryllium window

Correct Answer: Crystal monochromator (e.g., graphite or Ge) using Bragg reflection

Q17. Which set of operating conditions is typical for a sealed-tube Cu X-ray source in XRPD?

• 5 kV, 2 mA
• 20 kV, 2 A
• 40 kV, 30 mA
• 120 kV, 500 mA

Correct Answer: 40 kV, 30 mA

Q18. To reduce fluorescence from Fe-containing samples in powder diffraction, which target is commonly preferred and why?

• Cu, because its Kα energy is higher than Fe K-edge
• Co, because its Kα energy is below the Fe K-edge, minimizing Fe fluorescence
• Mo, because it produces the longest wavelength
• Ag, because it eliminates bremsstrahlung

Correct Answer: Co, because its Kα energy is below the Fe K-edge, minimizing Fe fluorescence

Q19. Half-value layer (HVL) in the context of X-ray beams is defined as the thickness of a material that:

• Doubles the photon energy
• Reduces the beam intensity to 50% of its original value
• Eliminates characteristic lines
• Produces monochromatic radiation

Correct Answer: Reduces the beam intensity to 50% of its original value

Q20. Beam collimation in X-ray production primarily serves to:

• Increase tube current without heating
• Reduce beam divergence to improve resolution at the cost of some intensity
• Raise the Kα energy of the target
• Eliminate the heel effect

Correct Answer: Reduce beam divergence to improve resolution at the cost of some intensity

Download