Electromagnetic Waves: Mediums, Study notes of Law

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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

Electromagnetic SpectrumThe^ Electromagnetic Spectrum illustrates the range of wavelengths and frequencies of electromagnetic waves. Notice that some kinds of waves have overlapping ranges

Notice the changes in the frequency of the wavelengths in the spectrum

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

Changes in Mediums: Light Waves

 When light waves strike an object, some of the waves are absorbed by the object, some are reflected by it, and some might pass through it (transmitted).  What happens to light when it strikes the object depends on the material of the object.

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.

If the surface is smooth and even, the reflection will be clear.

If the surface is uneven, like ripples in a

pond, the light is reflected in many

directions and the image is not clear.

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

You can see objects outside because light is transmitted through the glass You can see the glass and your reflection in it because light is reflected off the glass The glass feels warm when you touch it because some of the light is absorbed by the glass

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