A diffraction grating is illuminated using a lamp that has red (656 nm) and violet (434 nm) lines...

A diffraction grating is illuminated using a lamp that has red (656 nm) and violet (434 nm) lines in its spectrum. The grating has 4000 lines/cm. A screen is placed at a distance of 12.0 m from the grating.

(a) In how many orders do you expect to see both red and violet lines?

(b) Find the distance on the screen between the third order red and the fifth order violet.