Does the value of fringe width in Young's double slit experiment changes if we place a thin film in front of point source of another refractive index?

Dear student 

It depends upon the wavelength or frequency of light. Intensity of the incident light has no relation with the fring width in any case. It's the measure of the power incident on a surface per unit area. The brightness of the fringes are affected by intensity of incident light not the fringe width.