Question

Which one of the following electromagnetic radiations has minimum wavelength ?

• A. Ultraviolet
• B. X-rays
• C. Microwaves
• D. γ-rays

Hint:

Remember the order of the electromagnetic spectrum: "Roman Men Invented Very Unusual X-ray Guns" (Radio, Microwaves, Infrared, Visible, Ultraviolet, X-rays, Gamma rays). This mnemonic lists the radiations in order of decreasing wavelength and increasing frequency/energy.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is classified by wavelength, frequency, or energy. Wavelength (\(\lambda\)) and frequency (\(f\)) are inversely related (\(c = f\lambda\)), and energy (\(E\)) is directly proportional to frequency (\(E = hf\)). Therefore, minimum wavelength corresponds to maximum frequency and maximum energy.
Step 2: Detailed Explanation:
Let's arrange the given electromagnetic radiations in order of decreasing wavelength (or increasing frequency/energy):
1. Microwaves: Wavelengths range from about 1 meter to 1 millimeter. They have longer wavelengths and lower energy than the other options.
2. Ultraviolet (UV): Wavelengths are shorter than visible light, typically from 400 nm to 10 nm.
3. X-rays: Wavelengths are shorter than UV rays, typically from 10 nm to 0.01 nm.
4. γ-rays (Gamma rays): They have the shortest wavelengths in the entire electromagnetic spectrum, typically less than 0.01 nm (or 10 picometers). They are the most energetic form of electromagnetic radiation.
The order from longest to shortest wavelength is: Microwaves>Ultraviolet>X-rays>γ-rays.
Step 3: Final Answer:
Among the given options, γ-rays have the minimum wavelength. Therefore, option (D) is correct.