Calculating Number of Fringes with Wavelength and Slit Width

[StudentofPhysics]

1. How many dark fringes will be produced on either side of the central maximum if light ( = 553 nm) is incident on a single slit that is 5.1 10-6 m wide?



2. sin theta = m (lamba/ W)

lamba = wavelength
W = slit width
m - number of fringes



3. I have no idea how to do this without at least an L or theta.

Does anyone know what I am to do?

 

[StudentofPhysics]

ok, i decided to try the slit width divided by the wavelength. This gave me the correct answer.

Is this because this is a way to determine how many wavelengths will fit through the slit and therefore how many fringes there will be?

I just want to make sure I am using a correct theory here and that I did not just get lucky.