Measurement of the wavelength of monochromatic source of light with the help of Fresnel’s Bi prism

1. The angle of the bi prism is approx:
2. Order of distance between virtual sources in the bi prism experiment is:
3. The light Sources S1 and S2 are:
4. In the formula for calculating the wavelength of the light source from Fresnel’s bi Prism the distance D is between: