# Order of magnitude of Grating Spacing!

1. Homework Statement

Some microowaves (EM radiation) have wavelength of 3 cm. What would be the order of magnitude of grating spacing needed to observe these ?

2. Homework Equations

n$$\lambda$$ = d sin$$\theta$$

3. The Attempt at a Solution

First of all, I am not really sure if I was using the correct equation for that question but all what I am doing is about the diffraction grating spectrometer, gas spectra wavelength of light. In that question there was no angle so I can find n. The only thing is the wavelength given. I do not want you to solve it. I just want you to lead me to where should I go ?