Angular width of first-order visible spectrum

[Bolter]

Homework Statement

See image attached below

Relevant Equations

dsin(theta) = m*lambda

This is a diffraction grating problem I have been given that I am trying to answer

Made a attempt at it and just wanted to see if I done this correctly or not? I get an angular width of 0.71 degrees which is very small

Any help is much appreciated! Thanks

 

[etotheipi]

You switched from lines per millimetre to lines per centimetre at the start.

 

[Bolter]

You switched from lines per millimetre to lines per centimetre at the start.

Oh shoot yes you're right I don't know what I was thinking there. This must change the whole answer then. I get my distance between adjacent slits to be 1/415,000 m = 2.409... x 10^-6 m

Running through the same process but with new d value now, I get the angular width to be 7.33 degrees now?