0 Members and 8 Guests are viewing this topic.
Why not?
It can't diffract because it is constrained to travel along the length of the string. If you "bend" the string around a rigid fixture, the wave may reflect from the fixture but won't go around it, but if you bend the string with a flexible post, the attenuated wave will travel beyond the post. So what?
While both diffraction and interference are phenomena related to light waves, they have key differences in their origin and characteristics.Diffraction:Cause: Occurs when a light wave encounters an obstacle or opening.Mechanism: The edges of the obstacle or opening act as sources of secondary wavelets, which spread out and interfere with each other.Pattern: The resulting pattern consists of bright and dark bands, with the intensity and width of the bands varying depending on the size and shape of the obstacle.Examples: Rainbows, the diffraction pattern of a single slit or double slit, and the formation of Fresnel zones.Interference:Cause: Occurs when two or more coherent light waves overlap.Mechanism: The crests and troughs of the waves combine, leading to constructive interference (where the amplitudes add up) and destructive interference (where the amplitudes cancel out).Pattern: The resulting pattern consists of alternating bright and dark bands with equal widths and high contrast.Examples: Young's double-slit experiment, thin-film interference in soap bubbles and oil slicks, and the formation of Newton's rings.
It doesn't seem to improve much from the last time I asked. Bard's alternative answers don't give much better answers.
It's all perfectly true, if a bit simplistic. What's your problem?
Wow, it's almost like Bard is just a chat bot, I wonder why that is?
In answer to the OP, I would say the problem is 'a lot of people' don't care enough to take the time to find out the difference or they have reading comprehension issues.
IMO, misleading online sources also played significant role here.
Diffraction without interference doesn't produce such patterns.
Quote from: hamdani yusuf on 10/12/2023 11:45:04Diffraction without interference doesn't produce such patterns.Look at an x-ray diffraction pattern.
Quote from: hamdani yusuf on 10/12/2023 13:49:49IMO, misleading online sources also played significant role here.Sources are easy enough to check. An easy way to check if something on the Internet is science or not is to go to a university site and see if they are teaching that 'something'.
https://en.wikipedia.org/wiki/Argument_from_authorityAn argument from authority (argumentum ab auctoritate), also called an appeal to authority, or argumentum ad verecundiam (argument against shame), is a form of argument in which the mere fact that an influential figure holds a certain position is used as evidence that the position itself is correct.[1] While it is not a valid form of logical proof,[1] it is a practical and sound way of obtaining knowledge that is generally likely to be correct when the authority is real, pertinent, and universally accepted.This argument has been considered a logical fallacy since its introduction by John Locke and Richard Whately.[4] In particular, this is a form of genetic fallacy; in which the conclusion about the validity of a statement is justified by appealing to the characteristics of the person who is speaking, such as in the ad hominem fallacy.[5] For this argument, Locke coined the term argumentum ad verecundiam (appeal to shamefacedness/modesty) because it appeals to the fear of humiliation by appearing disrespectful to a particular authority.[6]This qualification as a logical fallacy implies that this argument is invalid when using the deductive method, and therefore it can't be presented as infallible.[7] In other words, it's logically invalid to prove a claim is true because an authority has said it. The explanation is simple: authorities can be wrong, and the only way of logically proving a claim is providing real evidence and/or a valid logical deduction of the claim from the evidence.
After a while, I asked Google Bard again about the difference between diffraction and interference. This time I specifically mentioned light. What's the difference between diffraction and interference of light? QuoteWhile both diffraction and interference are phenomena related to light waves, they have key differences in their origin and characteristics.Diffraction:Cause: Occurs when a light wave encounters an obstacle or opening.Mechanism: The edges of the obstacle or opening act as sources of secondary wavelets, which spread out and interfere with each other.Pattern: The resulting pattern consists of bright and dark bands, with the intensity and width of the bands varying depending on the size and shape of the obstacle.Examples: Rainbows, the diffraction pattern of a single slit or double slit, and the formation of Fresnel zones.Interference:Cause: Occurs when two or more coherent light waves overlap.Mechanism: The crests and troughs of the waves combine, leading to constructive interference (where the amplitudes add up) and destructive interference (where the amplitudes cancel out).Pattern: The resulting pattern consists of alternating bright and dark bands with equal widths and high contrast.Examples: Young's double-slit experiment, thin-film interference in soap bubbles and oil slicks, and the formation of Newton's rings.It doesn't seem to improve much from the last time I asked. Bard's alternative answers don't give much better answers.
Interference and diffraction in light, while related, are distinct phenomena caused by different mechanisms:Interference:Occurs when two or more light waves interact with each other.Requires coherent sources, meaning the waves have the same wavelength and are in phase (aligned peaks and troughs).Can be constructive (bright areas) or destructive (dark areas) depending on the relative phase difference between the waves.Creates distinct fringe patterns with alternating bright and dark bands.Examples: double-slit experiment, Newton's rings.Diffraction:Occurs when a light wave encounters an obstacle or opening.Caused by the bending of the wavefront due to secondary wavelets generated from different parts of the wave passing the obstacle.Affects the wave's propagation by spreading it out beyond its original path.Creates bending and fading around the edges of the obstacle.Examples: light passing through a narrow slit, shadows with blurred edges.
Interestingly, Richard Feynman had a unique perspective on the difference between interference and diffraction, suggesting that it's more a matter of context and usage than a clear physical distinction. He famously stated:"No one has ever been able to define the difference between interference and diffraction satisfactorily. It is just a question of usage, and there is no specific, important physical difference between them."Feynman argued that both phenomena arise from the same underlying principle ? wave interaction. What we call interference or diffraction depends on the number of wave sources involved:Interference: When only a few sources (typically two) interact, we typically refer to it as interference. This leads to the characteristic fringe patterns observed in experiments like the double-slit experiment.Diffraction: When we deal with a large number of sources (like the edges of an object), the interaction becomes more complex and diffuse. This is generally referred to as diffraction. The spreading and bending of light around edges exemplify this phenomenon.While Feynman acknowledged the practical distinction in usage, he emphasized that both aspects arise from the same fundamental wave behavior. This perspective highlights the interconnectedness of wave phenomena and encourages deeper understanding beyond rigid labels.It's important to note that while Feynman's view offers a nuanced perspective, many other physicists do differentiate between interference and diffraction based on the specific mechanisms involved. The table I provided earlier reflects this more common approach, which offers a clear framework for understanding both phenomena.Ultimately, both perspectives are valid and have their own merits. Choosing the approach that best suits your learning style and level of understanding is key.