ATAR Notes: Forum

HSC Stuff => HSC Science Stuff => HSC Subjects + Help => HSC Physics => Topic started by: Matth3wliu on June 01, 2020, 03:29:52 pm

Title: Diffraction
Post by: Matth3wliu on June 01, 2020, 03:29:52 pm

Hey all,

Can someone please explain why wavelength affects diffraction?


Thanks, Matt

Title: Re: Diffraction
Post by: Coolmate on June 01, 2020, 06:50:02 pm

Quote from: Matth3wliu on June 01, 2020, 03:29:52 pm

Hey all,

Can someone please explain why wavelength affects diffraction?


Thanks, Matt

Hey Matt! :)

Wavelength does affect diffraction.

The visible light part of the light spectrum, ranges from 400nm to 700nm, as wavelength decreases so too does the angle of diffraction, but if the wavelength increases so too does the angle of diffraction:

+💡Increasing Wavelength = Increasing Defraction rate
-💡Decreasing Wavelength = Decreasing Defraction rate

For Example, a wave coloured red, has a wavelength of about ~635nm - 700nm. According to its length, it will have a larger defraction rate than a blue wavelength which is around ~400nm - 450nm

Why it affects diffraction --> Because of the size of the wavelength

You can have a go at this PHET simulation to help with understanding:
https://phet.colorado.edu/sims/html/wave-interference/latest/wave-interference_en.html

I hope this makes sense and helps
Coolmate 8)

Title: Re: Diffraction
Post by: Einstein_Reborn_97 on June 01, 2020, 07:10:03 pm

Quote from: Matth3wliu on June 01, 2020, 03:29:52 pm

Hey all,

Can someone please explain why wavelength affects diffraction?


Thanks, Matt

Hey Matt,

I'd like to just add to what Coolmate has said.
A wave must have a wavelength that is either equal or larger in size to an opening/gap/slit in order to observe diffraction.
A simple ratio you can use to check this is \(\frac{λ}{w}\) (w = size of opening). If \(\frac{λ}{w}≥1\) diffraction will occur.

Hope that helps ;)

Title: Re: Diffraction
Post by: Matth3wliu on June 02, 2020, 10:13:25 am

Thank you guys!