Differences

This shows you the differences between two versions of the page.

--- courses:ast100:0.4 [2026/02/01 08:11] – [How Telescopes Work] asad
+++ courses:ast100:0.4 [2026/02/01 08:12] (current) – [What is Light?] asad
@@ Line 5: / Line 5: @@
 {{https://resource.isvr.soton.ac.uk/spcg/tutorial/tutorial/Tutorial_files/light1.gif?nolink}}
-As shown in the animation above, light is a form of electromagnetic radiation (or waves) composed of rapidly fluctuating electric (**E**) and magnetic (**B**) fields that vibrate perpendicular to one another and to their direction of travel, moving through the vacuum of space at a constant, finite speed, $c$. This radiation arises whenever electrically charged particles, such as **electrons**, undergo **acceleration** or a change in motion; for instance, in a lightning bolt, accelerated charged particles release energy as visible light.
+As shown in the bottom panel of the animation above, light is a form of electromagnetic radiation (or waves) composed of rapidly fluctuating electric (**E**) and magnetic (**B**) fields that vibrate perpendicular to one another and to their direction of travel, moving through the vacuum of space at a constant, finite speed, $c$. This radiation arises whenever electrically charged particles, such as **electrons**, undergo **acceleration** or a change in motion; for instance, in a lightning bolt, accelerated charged particles release energy as visible light.
 We characterize these waves by their **wavelength**—the distance between two consecutive wave crests—and their **frequency**, which is the number of crests that pass a specific point every second. These two properties share an inverse relationship, meaning that if you double the frequency, the wavelength is cut in half, because their combination must always equal the constant speed of light. Additionally, light behaves as discrete packets of energy known as photons, where the amount of energy carried is directly proportional to the frequency; consequently, radiation with a high frequency and short wavelength carries significantly more energy than radiation with a low frequency and long wavelength. The wavelength is measured in meters, frequency in hertz (Hz, cycles per second), and energy in joules.