###### Question 1 of 1

Interference fringes produced using white light in a double-slit arrangement. When a mica sheet of uniform thickness of the refractive index 1.6 (relative to air) is placed in the path of light from one of the slits, the central fringe moves by a distance. This distance is equal to the width of 30 interference bands if the light of wavelength 4800 $\stackrel{\mathrm{o}}{\mathrm{A}}$ is used The thickness (in $\mu$m) of mica is —

1.  90

2.  12

3.  14

4.  24