PHY137H5 Lecture Notes - Lecture 11: Electromagnetic Spectrum, Photon, Plane Wave
Document Summary
Why is it important? the speed of an electromagnetic wave is used in: Special relativity the speed of an electromagnetic wave in a vacuum is the universal speed limit. Relevance the spectrum of electromagnetic radiation from longest to shortest wavelength. Why is it important? the longest em waves are radio waves, and the shortest are gamma rays shorter wavelengths=higher frequency=higher energy radios and tv"s remote controls x-ray scanners (among other things) It explains why uv rays damage our skin. Knowing how it works allows us to better understand space. Relevance showing an em wave as a sine function here"s how we represent waves as sine functions where a is the amplitude, f is the frequency (in hertz), and t is the time (in seconds). In the case of an em wave, the amplitude is equal to the magnetic field intensity (magnetic part) or the electric intensity (electric part).
