Doubts in double slit experiment

In summary, when the path difference between the two slits is equal to or smaller than the wavelength of light, constructive interference will occur and the light will be brightest at the central peak. The brightness decreases as the path difference increases because the waves are constructive interference at different amplitudes.
  • #1
journeytospace
10
0
hi all...it is said that constructive interference happens when the path difference is nlambda and i think wavelength,frequency and amplitude of light going through both slits is the same then
why is the central maxima is the brightest spot?
why the brightness decreases when n increases?

Since the amplitude is same why there is difference in the brightness of the bright fringes?
 
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  • #2
Because the amplitudes of the waves that constructively interfere are different at 'different n'.
 
  • #3
why does the amplitude changes and why the central fringe is the brightest one(why not other fringes)..can u explain in detail about it?..
 
  • #4
Each of the slits acts as a radial light source (in the right half of the plane). You can think of it like this: Lines of equal field intensity are semi-circles. The intensity at a point on the circle is inversely proportional to its size, or in other words its distance from the point source. Now if you draw the screen, the screen's center is on a smaller circle (drawn around the source) than a point further away is.
 
  • #5
journeytospace said:
hi all...it is said that constructive interference happens when the path difference is nlambda and i think wavelength,frequency and amplitude of light going through both slits is the same then
why is the central maxima is the brightest spot?
why the brightness decreases when n increases?

Since the amplitude is same why there is difference in the brightness of the bright fringes?

This has nothing to do with quantum mechanics. I'm moving it out of there.

Zz.
 
  • #6
The diffraction pattern of a double-slit is a actually a convolution between the characteristic sinc^2 single-slit pattern that has a bright central peak and secondary peaks at either side of the central peak, and the characteristic cos^2 fringes.

The finite number of visible peaks comes about because of the finite width of the slits. As one reduces the width of the slits, the diffraction pattern will approach the ideal cos^2 case.

trinitron said:
Each of the slits acts as a radial light source (in the right half of the plane).
This is wrong, slits don't act like point sources, they have a characteristic sinc^2 emittance profile. The reason the brightest fringe is in the centre is for the same reason single-slit diffraction has a bright central peak - it all boils down to the Huygens-Fresnel principle of secondary wavelets.

Claude.
 
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1. What is the double slit experiment and why is it important?

The double slit experiment is a classic experiment in physics that demonstrates the wave-particle duality of light and matter. It involves shining a beam of light or particles through two parallel slits and observing the resulting interference pattern on a screen. It is important because it helps us understand the fundamental nature of light and matter, and has implications in fields such as quantum mechanics and optics.

2. What is the cause of the interference pattern observed in the double slit experiment?

The interference pattern observed in the double slit experiment is caused by the wave-like behavior of particles and their ability to interfere with each other. When particles pass through the two slits, they create diffraction patterns that overlap and produce areas of constructive and destructive interference, resulting in the pattern observed on the screen.

3. What factors can affect the interference pattern in the double slit experiment?

The interference pattern in the double slit experiment can be affected by several factors, including the wavelength of the particles, the distance between the slits, and the distance between the slits and the screen. Other factors such as the material and size of the slits, as well as external factors like temperature and air currents, can also affect the pattern.

4. Can the double slit experiment be performed with any type of particles?

Yes, the double slit experiment can be performed with any type of particles, including electrons, protons, and even large molecules like buckyballs. However, the size and behavior of the particles may affect the results, so adjustments to the experimental setup may be necessary.

5. What are some real-world applications of the double slit experiment?

The double slit experiment has many real-world applications, including in the development of new technologies such as electron microscopes and particle accelerators. It also has implications in fields such as quantum computing, cryptography, and communication. Additionally, the experiment has been used to study the behavior of matter and light in various conditions, helping us gain a better understanding of the fundamental principles of the universe.

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