In the biprism experiment, the light of wavelength 520 nm is used to get an interference pattern on the screen. The fringe width changes by 1.3 mm when the screen is brought towards biprism by 50 cm. The distance between the virtual images of the slit will be
1
0.8 mm
2
0.2 mm
3
0.4 mm
4
More than one of the above
5
None of the above