Calculating Slit Width from Diffraction Pattern

[Octoshark]

Homework Statement

The diffraction pattern shown in the figure is produced by passing He-Ne laser light (λ = 632.8 nm) through a single slit and viewing the pattern on a screen 1.58 m behind the slit.

What is the slit width?

Homework Equations

a = {(wavelength)D}/(distance of minima)

The Attempt at a Solution

a = {(632.8 x 10^-9)(1.58)}/(.152)

Answer: slit width = 6.577 x 10^-6 which is very wrong.

I feel like my equation is definitely wrong.

 

[Doc Al]

The equation isn't bad, but "distance of minima" is the distance of the first minima from the center of the pattern. You can multiply the right hand side by 'm', then the distance will be from the center to the m'th minima.

See: http://hyperphysics.phy-astr.gsu.edu/Hbase/phyopt/sinslit.html#c1"

 

[Octoshark]

So by dividing by .076 instead of .152 I get 1.316 x 10^-5 which is incorrect. I must be misunderstanding you, sorry.

 

[Doc Al]

So by dividing by .076 instead of .152 I get 1.316 x 10^-5 which is incorrect.

0.076 would be the distance from the center to which minima?

 

[Octoshark]

Ahhh, got it. Thanks a bunch ;)