Question

X-rays are classified as hard and soft based on the following characters
A. Density
B. Current
C. Penetrating power
D. Wavelength
E. Frequency
Choose the correct answer from the options given below:

• A. A and B only
• B. D only
• C. B and E only
• D. C only

Hint:

Hard vs Soft X-Rays:
Hard X-Rays $\rightarrow$ High Energy, Short Wavelength, HIGH PENETRATING POWER (diagnostic bone/deep radiography).
Soft X-Rays $\rightarrow$ Low Energy, Long Wavelength, LOW PENETRATING POWER.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Classification of X-radiation by photon energy and penetrating capacity: hard X-rays (high kVp, short wavelength, high penetration) vs soft X-rays (low kVp, long wavelength, low penetration).
Key Formula or Approach:
\[ \text{Photon Energy } (E) = h\nu = \frac{hc}{\lambda} \propto \text{Penetrating Power} \]

Step 2: Detailed Explanation:
Physical classification of X-rays:
1. Hard X-rays: Produced at high kilovoltage (high kVp); have short wavelengths ($\lambda pprox 0.01 - 0.1 ext{ \AA}$), high photon energies, and High Penetrating Power capable of penetrating dense body tissues and bone.
2. Soft X-rays: Produced at low kilovoltage (low kVp); have longer wavelengths ($\lambda > 1 ext{ \AA}$), low photon energies, and Low Penetrating Power, easily absorbed by superficial soft tissues.
Therefore, the defining operational clinical criterion separating hard from soft X-rays is their Penetrating Power (C only).

Step 3: Final Answer:
Hence, X-rays are classified as hard and soft based on C only, matching option (D).