# Angular Width Of Central Diffraction

Chris18
350nm falls on a single slit of width of 0.20mm. What is the angular width of the central diffraction peak?

I think that the width should be equal to 2Θ, where Θ=arcsin(m*λ/d)... m=1 and we have λ=350*10^-9 and d= 0.20*10^-6...but when i do the calculations I get 1.75 and the arcsin is a maths error...Could anyone help me please?

Homework Helper
λ=350*10^-9 and d= 0.20*10^-6
Are those numbers in the same unit?

Chris18
λ=nm and d= mm

Homework Helper
Gold Member
Note 1 mm ≠ 10-6 m.

Chris18
Ok so I must have 10^-7 ?