- #1
foxx0775
- 1
- 0
Homework Statement
A parallel beam of mono-chromatic light (500nm) is incident on 2 long narrow slits: slit width is 0.1mm and the distance between slit centres is 0.3mm.
a) How many bright fringes cover the central diffraction maximum?
Homework Equations
Condition for constructive interference:
[tex]\Delta = 2d.cos\theta = 2m(\lambda\div2)[/tex]
Reduces to:
[tex]2d=m\lambda[/tex] as [tex] cos\theta=1[/tex] ?
The Attempt at a Solution
I get 1200 once I convert both[tex] d [/tex]and [tex]\lambda[/tex] into metres. Is this the right thing to do? I'm not sure this is the amount that cover the central maximum, what does this bit mean?
- - - Part b)
Homework Statement
Part b) Calculate the angle corresponding to the first diffraction minima
Homework Equations
[tex]sin\theta= ((2m-1)\lambda)\div2)\div d [/tex]
The Attempt at a Solution
Taking m as 1 because it is the first diffraction minima
Reduces to:
[tex]\theta = arcsin[ (5\times10^{-7}) / (6\times10^{-4}) ][/tex]
I get [tex]\theta[/tex] = 0.048 degrees
is this correct?
There is part c) but haven't attempted it yet, overall the whole question is allocated 14 marks.