The width of fringe is \( 2 \, \text{mm} \) on the screen in a double slits experiment for the light of wavelength of \( 400 \, \text{nm} \). The width of the fringe for the light of wavelength \( 600 \, \text{nm} \) will be:
\( 2 \, \text{mm} \)
\( 1.33 \, \text{mm} \)
\( 4 \, \text{mm} \)
\( 3 \, \text{mm} \)