Question

Light of wavelength 1 nm belongs to the following class of waves

• A. Radio waves
• B. Micro waves
• C. X-rays
• D. Gamma rays

Hint:

Memorize the approximate wavelength ranges for different parts of the electromagnetic spectrum.
Order of EM spectrum by increasing frequency (decreasing wavelength): Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma ray. (Mnemonic: "Roman Men Invented Very Unusual X-ray Guns" or similar).
Key conversions: $1 \text{ nm} = 10^{-9} \text{ m}$; $1 \text{ \AA} = 10^{-10} \text{ m} = 0.1 \text{ nm}$; $1 \text{ pm} = 10^{-12} \text{ m} = 0.001 \text{ nm}$.
$1 \text{ nm}$ is a common reference point often falling into the X-ray category.

Answer 1

The Correct Option is C

Electromagnetic Spectrum Classification (by wavelength):

• Radio waves: \( > 0.1 \, \text{m} \) (or \( > 1 \, \text{cm} \))
• Microwaves: \( 1 \, \text{mm} \) to \( 1 \, \text{m} \)
• Infrared (IR): \( 700 \, \text{nm} \) to \( 1 \, \text{mm} \)
• Visible light: \( 400 \, \text{nm} \) (violet) to \( 700 \, \text{nm} \) (red)
• Ultraviolet (UV): \( 10 \, \text{nm} \) to \( 400 \, \text{nm} \)
• X-rays: \( 0.01 \, \text{nm} \) to \( 10 \, \text{nm} \)
• Gamma rays: \( < 0.01 \, \text{nm} \) (some use \( < 0.1 \, \text{nm} \))

Given: \( \lambda = 1 \, \text{nm} = 1 \times 10^{-9} \, \text{m} \)

Comparison:

• Radio waves: Far longer wavelength ⇒ Not applicable.
• Microwaves: Longer than 1 nm ⇒ Not applicable.
• Infrared and Visible: Still longer than 1 nm ⇒ Not applicable.
• Ultraviolet (UV): Shortest UV is around 10 nm ⇒ 1 nm is shorter ⇒ Not UV.
• X-rays: \( 0.01 \, \text{nm} \) to \( 10 \, \text{nm} \) ⇒ 1 nm lies clearly in this range ✅
• Gamma rays: Wavelengths less than 0.01 nm ⇒ 1 nm is too long.

Conclusion: Based on standard classifications, a wavelength of \( 1 \, \text{nm} \) is best identified as:

\[ \boxed{\text{X-rays}} \]