Which of the following quantities remains unchanged when a beam of light travels from an optically rarer medium to an optically denser medium?

💡 Solution & Explanation

When light travels from an optically rarer medium to a denser medium, its speed decreases and its wavelength shortens proportionally, but its frequency remains completely unchanged because frequency depends strictly on the source emitting the wave. Other properties like amplitude can vary due to reflection and absorption phenomena at the boundary.