Question

Which of the following statements is/are correct for electromagnetic (EM) radiation?

• A. At room temperature, natural objects emit EM radiation
• B. Blackbody radiation is proportional to square of the absolute temperature of the body
• C. Wien’s displacement law provides the dominant wavelength of EM emission
• D. EM energy decreases with increase in wavelength

Hint:

Electromagnetic radiation has properties that depend on the temperature of the emitting object. As temperature increases, the energy and frequency of emitted radiation increase, and the peak wavelength decreases.

Answer 1

The Correct Option is A, C, D

Understanding the Properties of EM Radiation
Option (A): This is correct because all objects at temperatures above absolute zero, including those at room temperature, emit electromagnetic radiation, although this radiation is primarily in the infrared region for most objects at room temperature.

Option (B): This is incorrect because blackbody radiation is not directly proportional to the square of the absolute temperature. Instead, it is proportional to the fourth power of the temperature, as described by the Stefan-Boltzmann law.

Option (C): This is correct because Wien’s displacement law describes how the dominant wavelength (or peak wavelength) of emitted radiation shifts with temperature, with higher temperatures corresponding to shorter wavelengths.

Option (D): This is correct because the energy of electromagnetic radiation is inversely proportional to its wavelength, meaning that as wavelength increases, energy decreases. This is consistent with the equation \(E = \frac{hc}{\lambda}\), where \(E\) is energy, \(\lambda\) is wavelength, \(h\) is Planck's constant, and \(c\) is the speed of light.