Electromagnetic Waves: Mediums, Study notes of Law

Download Electromagnetic Waves: Mediums and more Study notes Law in PDF only on Docsity! Electromagnetic Waves: Mediums Essential Question: How are the characteristics of electromagnetic waves affected by medium? Let’s Review Electromagnetic Waves Waves that DO NOT NEED matter (medium) to transfer energy Examples: radiation, TV & radio waves, X-rays, microwaves, lasers, energy from the sun, visible light Electromagnetic waves are considered transverse waves because they have similar characteristics. They have a crest, trough, wavelength, and amplitude Notice the changes in the frequency of the wavelengths in the spectrum Distributed Summarizing With a partner, discuss the following questions: How is an electromagnetic wave different from a mechanical wave (sound)? Name some examples of electromagnetic waves. Compare the wavelength and frequency of your examples (you may need to use electromagnetic spectrum diagram) Changes in Mediums  Waves do not just stop when they reach the end of a medium or when they meet an obstacle in the path.  These behaviors were first introduced in the lesson on sound. They include: absorption, reflection, diffraction, and refraction.  We will be examining these behaviors in regards to light waves When a beam of light shines through the air, particles in the air absorb some of the energy from the light. As a result, the beam of light becomes dim. The farther the light travels from its source, the more it is absorbed by particles, and the dimmer it becomes. Changes in Mediums: Absorption of Light Waves Absorption will be discussed more in the next essential question on how light is detected by the human eye. Changes in Mediums Reflection of Light Waves  Reflection occurs when a wave strikes an object or surface and bounces off.  Light waves reflecting off an object allow you to see that object.  Light reflected from any surface always follows a simple rule: the angle with which the ray of light hits the surface is the same with which the ray of light will be reflected (Law of Reflection) Wave Interactions Reflection Wave bounces { off a material q new direction. and goes ina Notice: the angle with which the ray of light hits the surface is the same with which the ray of light is reflected Reflected Beam Incident Beam Angle of Reflection Angle of Incidence Changes in Mediums Diffraction of Light Waves  Diffraction is the bending of waves around a barrier.  The amount a wave diffracts depends on its wavelength and the size of the barrier or the opening.  The greatest amount of diffraction occurs when the barrier or opening is the same size or smaller than the wavelength source SL Sa) fey need http://library.thinkquest.org/19537/Physics6.html icra Ra ly EEA EE EE Eee Demin Interactions — bends around or goes through a hole in a material. ) x a] When plane waves go through a small hole, they become circular waves. Changes in Mediums Refraction of Light Waves  Refraction is the bending of a wave as it moves from one medium into another  The speed and wavelength of a wave changes during refraction (velocity changes) The speed of light varies depending on the material through which the waves are traveling. When a wave enters a new material at an angle, the part of the wave that enters first begins traveling at a different speed from that of the rest of the wave. Refraction is what gives the illusion of a bent straw or spoon in a clear glass of water. Light waves travel faster in air than in water, so as it passes through the water, it slows down and appears to bend.