B Question about double-slit experiment

[Jason Ko]

TL;DR Summary

Will the fringes be brighter if I use a raser with higher intensity? And can I improve the experiment by using higher wavelength incident rays so as to observe more bright fringes?

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[kuruman]

If you use a laser of higher intensity the locations where bright fringes appear will receive more photons per second so they will be brighter.

Why do you think that increasing the wavelength will increase he number of bright fringes? What equation do you have in mind? Also, in what way do you think the experiment will be improved if you increase the number of bright fringes?

 

[Jason Ko]

If you use a laser of higher intensity the locations where bright fringes appear will receive more photons per second so they will be brighter.

Why do you think that increasing the wavelength will increase he number of bright fringes? What equation do you have in mind? Also, in what way do you think the experiment will be improved if you increase the number of bright fringes?

The diffraction effect will enhance as the wavelength has increased, so the bright fringes will span wider. If the number of bright fringes has increased, the measurement will be more accurate.

 

[kuruman]

The diffraction effect will enhance as the wavelength has increased, so the bright fringes will span wider. If the number of bright fringes has increased, the measurement will be more accurate.

I repeat, what mathematical equation says that the number of fringes increases as the wavelength increases? You need to understand this point before you start thinking about increasing the accuracy of the experiment.

Also, you did not explain why more fringes means more accurate measurement. What exactly will you be measuring that will have its accuracy increased when you have more bright fringes?

 

[Jason Ko]

As I'll measure the distance spanned by several bright fringes and then determine the fringe separation. I think more fringes will lead to a better evaluation of fringe separation.

 

[Jason Ko]

I repeat, what mathematical equation says that the number of fringes increases as the wavelength increases? You need to understand this point before you start thinking about increasing the accuracy of the experiment.

Also, you did not explain why more fringes means more accurate measurement. What exactly will you be measuring that will have its accuracy increased when you have more bright fringes?

I think I've made thing wrong. mλ=asinθ, larger wavelength means larger θ, so fewer fringes will be formed.

 

[kuruman]

I think I've made thing wrong. mλ=asinθ, larger wavelength means larger θ, so fewer fringes will be formed.

Now you got the idea. So if you want to have more fringes, you have to decrease the wavelength.

 

[Jason Ko]

Now you got the idea. So if you want to have more fringes, you have to decrease the wavelength.

Thks a lot!