X-rays with high photon energies (above 5–10 keV) are called hard X-rays, while those with lower energy (and longer wavelength) are called soft X-rays. Due to their penetrating ability, hard X-rays are widely used to image the inside of visually opaque objects. Radiation Dosimetry.

In X-rays of wavelengths 4 A o , 1 A o , 0 . 1 A o , which one is hardest?

The penetrating power of X-rays depends upon their wavelength. The frequency of the longer-wavelength X-rays is lower and so their energy is smaller. Hence, their penetrating power is weaker and they are called ‘soft’ or ‘less-penetrating’ X-rays. The penetrating power of the shorter-wavelength X-rays is stronger, and they are called ‘hard’ or ‘highly penetrating’ X-rays. From the given wavelength of 4 A ∘ , 1 A ∘ and 0 . 1 A ∘ we can say penetrating power of 0 . 1 A ∘ is more as compared to 4 A ∘ and 1 A ∘ hence X-ray of wavelength 0 . 1 A ∘ will be hardest X-ray.

Two X-rays have wavelengths 10 A o and 1 A o . Which one will be hard X-ray?

The penetrating power of X-rays depends upon their wavelength. The frequency of the longer-wavelength X-rays is lower and so their energy is smaller. Hence, their penetrating power is weaker and they are called ‘soft’ or ‘less-penetrating’ X-rays. The penetrating power of the shorter-wavelength X-rays is stronger, and they are called ‘hard’ or ‘highly penetrating’ X-rays. From the given wavelength of 10 A ∘ and 1 A ∘ we can say penetrating power of 1 A ∘ is more as compared to 10 A ∘ hence X-ray of wavelength 1 A ∘ will be hard X-ray.