Question

Electromagnetic radiation has an energy of 15 keV. Then this radiation belongs to which region of electromagnetic waves?

(a) X rays

(b) Infrared rays

(c) Gamma rays

(d) UV rays

I had been asked this question during an online interview.

Enquiry is from Electromagnetic Spectrum topic in division Electromagnetic Waves of Physics – Class 12

Answer 1

Correct choice is (a) X rays

Easiest explanation: Given: Energy (E) = 15 keV

The required equation ➔ λ(in Å)=\( \frac {hc}{E(in \, eV)}\)

λ=\(\frac {12400}{15 \times 10^3}\)

λ=0.826 Å=0.826 × 10^-10  m

X rays cover wavelengths ranging from above 10^-8 m to 10^-13 m. Therefore, this electromagnetic radiation belongs to the region of X rays.