Why does wavelength affect diffraction?

In summary: However, the extent of diffraction may vary depending on the specific properties of the medium through which the wave is traveling. For example, water waves may diffract more easily than electromagnetic waves due to the differences in their properties. Overall, the concept of wavelength affecting diffraction is applicable to all types of waves. In summary, the longer the wavelength of a wave, the more easily it can bend around an obstacle. This is because, if we think of light as a wave, it makes sense that it would not travel in straight lines and would instead diffract around objects. This concept applies to all types of waves, though the extent of diffraction may vary depending on the properties of the medium.
  • #1
atyy
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This question came up in the biology section
https://www.physicsforums.com/threads/explain-different-types-of-light-microscopy.833990/.

Q1: The longer the wavelength of a wave, the more easily it bend around an obstacle. I do understand the mathematics, but is there any intuition for it?

Q2A: Is this an acceptable explanation, or is it misleading?

"If light were fundamentally a ray, then it makes sense that it would travel in straight lines. But if you think light is a wave, then it makes sense that it would not travel in straight lines. After all, if you put an obstacle in the path of waves in the sea, the waves can go around the obstacle. The bigger the obstacle, the less the waves can go around it. On the other hand, the bigger the wavelength, the smaller the obstacle is relative to the wave, so this gives some intuition as to why wavelength affects bending around an obstacle."

Q2B: If the above is acceptable, is it acceptable for all wave diffraction, or only for some, eg. ok for water waves or air, but not for electromagnetic waves?
 
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  • #2
atyy said:
Q2A: Is this an acceptable explanation, or is it misleading?

"If light were fundamentally a ray, then it makes sense that it would travel in straight lines. But if you think light is a wave, then it makes sense that it would not travel in straight lines. After all, if you put an obstacle in the path of waves in the sea, the waves can go around the obstacle. The bigger the obstacle, the less the waves can go around it. On the other hand, the bigger the wavelength, the smaller the obstacle is relative to the wave, so this gives some intuition as to why wavelength affects bending around an obstacle."

Sure, that's acceptable. Light is just a really short wavelength EM wave, so if you think about long-wavelength radio waves, they do indeed diffract around everyday objects.

atyy said:
Q2B: If the above is acceptable, is it acceptable for all wave diffraction, or only for some, eg. ok for water waves or air, but not for electromagnetic waves?

It should apply to all types of waves.
 

1. Why does the wavelength of light affect diffraction?

Wavelength affects diffraction because it determines the spacing between the waves of light. When the wavelength is larger, the waves of light are further apart and cause less diffraction. When the wavelength is smaller, the waves are closer together and cause more diffraction.

2. How does diffraction change with different wavelengths of light?

Diffraction increases as the wavelength of light decreases. This is because shorter wavelengths have a smaller distance between the waves, causing them to interfere with each other more and create a greater diffraction effect.

3. What is the relationship between wavelength and the angle of diffraction?

As the wavelength of light increases, the angle of diffraction decreases. This means that longer wavelengths have a smaller angle of diffraction, while shorter wavelengths have a larger angle of diffraction.

4. Why does wavelength affect the amount of diffraction in a single slit experiment?

In a single slit experiment, the width of the slit is comparable to the wavelength of light. When the slit is smaller than the wavelength, the amount of diffraction increases, resulting in a wider diffraction pattern. When the slit is larger than the wavelength, the amount of diffraction decreases and the pattern becomes narrower.

5. How does the wavelength of light affect the diffraction grating pattern?

The spacing between the lines of a diffraction grating determines the amount of diffraction. As the wavelength of light increases, the spacing between the lines must also increase in order to maintain the same angle of diffraction. This means that longer wavelengths will result in a wider and more spread out diffraction pattern, while shorter wavelengths will result in a narrower and more concentrated pattern.

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