# Diffraction Notes That Have Been Made By Me - Physics - Notes

1406 words - 6 pages

Physics 30 Lesson 12 Diffraction Gratings
Poisson’s bright spot
Thomas Young published the results from his double-slit experiment (Lesson 11) in 1807 which put the wave theory of light on a firm footing. However, so strong was Newton’s reputation and his corpuscular theory of light that Young’s results were not accepted until more than ten years later when, in 1819, Augustin Fresnel (1788–1827) presented to the French Academy a wave theory of light that predicted and explained interference and diffraction effects. (Refer to Pearson pages 691 to 692.)
Almost immediately after Fresnel introduced his wave theory, Simeon Poisson (1781–1840) pointed out what at first appeared as a counter-intuitive inference: that according to Fresnel's wave theory, if light from a point source were to fall on a solid disk, then light diffracted around the edges should constructively interfere at the center of the shadow. In other words, a bright spot should appear in the center of the shadow. That prediction seemed very unlikely. After attempting the experiment and failing to demonstrate the existence of a bright spot, Poisson claimed that he had refuted Fresnel’s theory.
But when the experiment was redone by Francois Arago in 1818, the bright spot was seen at the very center of the shadow! This was strong evidence for the wave theory and it was ironically referred to as Poisson’s Bright Spot. To the right is a photograph of the shadow cast by a coin using a (nearly) point source of light (a laser in this case). The bright spot is clearly visible at the center. Note that there are also bright and dark fringes beyond the shadow. These resemble the interference fringes of a double slit. Indeed, they are due to interference of waves diffracted around different parts of the disk, and the whole is referred to as a diffraction pattern.
A diffraction pattern exists around any sharp object illuminated by a point source, as shown in the photograph of a razor illuminated with laser light. We are not always aware of diffraction effects in our everyday life since most sources of light in everyday life are not point sources – so light from different parts of the source wash out the pattern.
Diffraction gratings
A large number of equally spaced parallel slits is called a diffraction grating. (Refer to Pearson pages 692 to 694.) Gratings are often made by ruling very fine lines on glass with a diamond tip. The spaces in between the lines serve as slits. Gratings containing more than 10 000 slits per centimetre are common today. A double slit apparatus produces an interference pattern where the fringes tend to be broad and relatively undefined. Diffraction gratings produce very sharp and well defined bright fringes and dark fringes. Check out the video clip called P30 L12 Diffraction interference in D2L. The video shows how different colours (i.e. wavelengths) of light are diffracted by different amounts.
A similar derivation like the one demonstrated for ...

## Notes About A Book We Have Studies In Year 11 Called "night" - English - Notes

498 words - 2 pages ... front of me, and I had not even blinked”. Chapter 4 - Elie is bent up and has encounter a French women. Pg 59 - Later in life he encounters the same women again. - Chlomo is full of rage. Pg 60 - One of the factors have been bombed. - Hearing a an ask “where is gods mercy now!!” Elie thinks from the gallows. Chapter 5 - All the jews began there solum service but Elie refused. Pg 45 - “But why would I bless?” - Began to believe that man was ...

## Long Physics Notes: Communications And Space: Not All Dot Points Covered In This Assignment

3320 words - 14 pages ... and inherited his notes when he died.Applied Brahe's notes to Copernicus' heliocentric ideas.His model stated that planets moved around the sun in elliptical orbits, and using this model could predict the motion of plants with great accuracy.Galileo:1564-1642Using his telescope, he discovered 4 of Jupiter's moons and that Venus had phases like the moon did.This could only be explained by a heliocentric model of the Solar System.Disproved the ...

## All About Me, And What I Have Been Through - Narritive - Personal Essay

936 words - 4 pages ... worries are linked to anxiety about drugs, permissive childrearing, hedonism, declining academic standards, the growth of the ghetto underclass, and our collective inability to compete with the Japanese. Taken together, these fears have convinced many sensible people that American society is on the skids. Crime rates have been the drop of decreasing to increasing over time. The Oxford Dictionary defines a crime as “an action or omission which ...

## Syntax Notes That Describe Biology - Biology - Notes

3421 words - 14 pages ... is a type of parallel sentence in which two parallel elements are set off against each other like equal weights on a scale. In reading the sentence aloud, one tends to pause between the balanced parts, each seeming equal. When writing a balanced sentence, be certain that both parts of the sentence have the clear parallels of form, that they appear parallel grammatically. In a balanced sentence, the phrases or clauses balance each other by virtue ...

## Hamlet By William Shakespeare Notes - English - Notes

2535 words - 11 pages ... questions emerge as the text progresses. What happens when you die? If you're murdered, then will you go to heaven? Do kings truly have a free pass to heaven? In Hamlet's mind the idea of dying isn't so bad. It's the uncertainty of the afterlife that frightens Hamlet away from suicide, even though he's obsessed with the notion. A turning point for Hamlet occurs in the graveyard scene in Act V. Before, Hamlet has been appalled and revolted by the moral ...

## Imagine That You Have Just Been Diagnosed As HIV Positive

701 words - 3 pages ... , those who are HIV positive may not have AIDS; therefore, if I had been diagnosed as HIV positive, I would establish a calm and strong confidence by reassuring myself of the fact that I may not necessary have as crucial of a situation as being diagnosed with AIDS, as long as I could put dramatic effort into taking care of my personal health and being cautious when engaging in any activity. Because of the lack of effective vaccines and antiviral ...

## Crim 133 Paper For Notes That Are From UBC And Not Shared By Anyone - UBC - Research Paper

890 words - 4 pages ... association with other risk factors Poverty Influences Parent Behavior · Adds additional stressors · Parents working 2 jobs · May reduce nurturing and consistent parenting · Aggressive discipline Association with Delinquent Peers · Peers influence social/emotional development · Delinquency predicted by delinquency of friends · Act in groups 3 Perspectives on Influence of Peers · Direct result of assoc. with deviant peers · Deviant youths seek similar ...

## Speaking Notes That Includes Discussions On Different Issues And Topics Around Perth WA - Rshs - Notes

1655 words - 7 pages ... dangerous job is to learn lifelong skills such as CPR and first aid. Another factors are: it will be a good workout for some people, they want to save people lives knowing that some people don’t have the skills like them, or to get a work experience from helping the community by doing these kinds of job. 2. I think teenagers should participate in volunteer work because in our generation most of the teenagers still rely on their parent. Doing ...

## Study Notes For The Apprenticeship Of Duddy Kravitz By Mordecai Richler

556 words - 3 pages ... Professionalism? Don't insult Family (6) Mocks Dingleman's father Wife is sick (8) Heavy drinker by 1947 (4)? Hersh Idealistic? Jerry Dingleman Makes up more successful brother? "doesn't live up here"? made-up? insecure? full of bs = covering up for something Inattentive Badly-Behaved Dysfunctional family? dad gone, food on table (cold ...

## Do You Consider That The Introduction Of The Citizen's Charter/service First Initiatives Over The Past Decade Have Made Any Improvements To The Law Of Public Administration ?

1655 words - 7 pages ... . It should be recognised that the charters, which have been introduced so far, are no alternatives to a genuine legal remedy capable of offering full compensation for any inconvenience or loss that may have been caused by the failure of a service, for example, a train turning up late to its destination. Therefore there is a lot of room for improvement in the governing of this area.BIBLIOGRAPHYTEXTBOOKS/ARTICLESCRAIG, P, P, ADMINISTRATIVE LAW, 4TH ...

## 2 Short Stories That Have Been Graded To Get You A High B Grade. You Can Use And Adapt It. - Carey College Year 11 - Story

1744 words - 7 pages Free ... made me feel ill, the thought of knowing someone unworthy of her love had claimed her… that it was not me. From then on i longed for her presence near mine, just to feel her aura next to mine and her warmth indulged in mine. I couldn’t sleep that night or eat or think straight. I just had to see her again, i needed to see her again. Days went past without a sight, the torture of every misconstrued person being the love of my life was tearing my ...

## This Is A Story About My Cultured Life And How I Have Been Affected By Discrimination - Puyallup High School - College Admission Essay

572 words - 3 pages ... day -- every day and saving the weekends for big carne asadas with the whole family made me realize that I love where I come from. I wouldn’t let anyone take that away from me. After that school year, I decided to go live with my mom again because I finally felt comfortable in my own skin (and the fact that I missed her a lot). Once in Georgia, I decided to start an organization called the “Hispanic Organization Promoting Education” or “HoPe” for ...

## Pay Attention Essay And Notes On Exercises That Help You Open Up Eyes More To World Around You - Cal Poly, Communications - Essay

602 words - 3 pages Free ... NOTES-20 pts. Throughout the three plus days of this exercise, please keep notes on your interactions with the materials included in each day’s assignment on Poly Learn, your experiences, and your thoughts and observations. You may type the notes or write them legibly by hand. When you turn the notes in to me, please contain them in a lightweight folder, or staple them securely. I will evaluate your notes on your commitment to the exercise and ...

## Sylaabus Verview For Precalculas - Chelmsford High School - Math Precalculas

946 words - 4 pages ... day of the test, he/she should take the MAKE UP TEST on the day of return. In excess of three days excused absence, test and work must be completed within three days of the students return to school. MAKE-UP WORK IS THE RESPONSIBILITY OF THE STUDENT! Tests can be made up during study hall, or by appointment. 3. Materials needed for class every day. a) Textbook: Physics: Principles and Problems b) Notebooks: Students are strongly advised to have ...

## Essay On Physics And Why I Want To Do It - Patriot High School - Essay

483 words - 2 pages Free ... preparation for graduate study not just in physics, but in all engineering and information/computer science careers. Through various activities, I have expanded my understanding of physics through the standoff of various problems that could only be solved with the knowledge of physics. For example, robotics has taken me through many situations where physics came in hand. In robotics, inertia affects the machine by controlling how much force they ...
Other Popular Examples