Width of a hair

[Vet track]

I need to use the equation wsinθ=nƛ to find w or width. I know θ = 0.6, and ƛ (wavelength?)=655nm.  But I have no idea what the n variable means. I looked it up on wiki (well wiki was one of the only site that recognized the equation) and it said "n is any integer". I'm fairly certain plugging in any integer will not produce the correct width. In an earlier equation (tanθ=y_n/L) n appears as a subscript. in this case the value I was plugging in was y₁ so should I plug 1 into   wsinθ=nƛ ? 

[studiot]

n is indeed an integer (any would be a tad ambitious)

Your equation suggests you are using 'the fringe method' for measuring hair width?

Here you get the light wave to be reflected back from the bottom of two glass plates (with the hair between propping one up at an angle) so that it interferes with itself, producing a pattern of dark and light 'fringes'

n refers to the fringes so n = 1 would be the first one and so on counting from the centre.

Obviously each finge will be displaced by a greater amount corresponding to n = 1,2,3..... but your chances of seeing 'any number' of fringes is low.

 

 

[Vet track]

I'm actually using a laser diffraction method, but, if I understand correctly, since I'm calculating for the first distance I should plug in 1 for n?

Thanks 

[studiot]

Even with lasers the first fringe is the strongest so unless you have good reason to use a different one yes n = 1.

 

How is this homework?

[J.C.MacSwell]

On 9/5/2018 at 2:40 PM, studiot said:

Even with lasers the first fringe is the strongest so unless you have good reason to use a different one yes n = 1.

 

How is this homework?

Looking at buying a new comb?