Lesson+31+&+32

**﻿Advancememt in Physics @ Dwight Englewood** **Director: Elise Burns** **TA: Sebastian Loh**

Light Waves
Light is elelctromagnetic because it is 3 dimensional they do not require a medium The iddle of the electromagnietc spectrum is light all magnetic radiation travel at the same speed 3x10^8 m/s symbol is "c" always travels in a straight line until acted on by an outisde force - linear propogation our range of frequencies 10^4 x to 10^24 hz radio - microwave - infared <>﻿ visible - UV - X Rays - Gamma

Optical Density how well light can travel through the medium the more optically dense the slower the light travels opaque no transmission obsorbs or reflects it all <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">translucent: partial transmission partial <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">transparent: atome takes the wave "jiggles a little" and remeitts the wave in the same direction with the same speed

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Diffraction light bends around obstacle or through an opening create or interfernce pattern <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">less difraction as opening decreases in size pattern will be cloer together.

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">central antinote is very bright (2x) double width fringe is the pattern to the right and left of central antinote.

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Diffraction grading has hndreds or thousands of slots per millimeteras <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">as (lambda ) decreases pattern gets closer <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Interference in 2 slits looks similar to diffraction <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">central antinde is same width and same brightness as fringe <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">distance b/w slits increases get closer pattern

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Types of Images <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Virtual images not where it seems to be, an allusion, in a mirrow for example the light is reflected and your brain puts it together <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">real images formed when lights isactually at the position it seems to be, can be projected

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">upright <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">inverted
 * <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Orientation **

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Enlarged <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Unchanged <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Reduced
 * <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Size **

**<span style="font-family: Tahoma,Geneva,sans-serif;">Location ** <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">relative to the optical plane and or the focal point

**<span style="font-family: Tahoma,Geneva,sans-serif;">Dispersion ** <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">wave lengths spread when they ass through a prism but look like a straight beam of light. <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">the red bends the least while violet bends the most <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">waves move fastest in the heat hotter = faster

**<span style="font-family: Tahoma,Geneva,sans-serif;">Waves of Nature ** <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">waves leave at the same angle they come <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">A two point source interference pattern always has a //nodal// and //antinodal// pattern. The change in wavelength alters the number of lines in a pattern. An increase in frequency shows more lines per centimeter and a smaller distances between. A decrease in frequency shows fewer lines per centimeter and a greater distance between each consecutive line.
 * 1) <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">reflection
 * 2) <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">refraction
 * 3) <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">diffraction

<span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">**Young** <span style="color: #ff0044; font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Young's equation is y • d / (m • L). This gives you the distance between each slit or light source.