A circular coil of radius 2 cm and 125 turns carries a current of 1 A . The coil is placed in a uniform magnetic field of magnitude 0.4 T . The axis of the coil makes an angle of $30^{\circ}$ with the direction of the magnetic field. The torque acting on the coil is $\alpha \times 10^{-4} \mathrm{~N} . \mathrm{m}$. The value of $\alpha$ is $\_\_\_\_$ .

$$ (\pi=3.14) $$

In a double slit experiment, when one of the slits is covered by a transparent mica sheet of refractive index 1.56 , the central fringe shifts to the position of $7^{\text {th }}$ bright fringe, obtained with both slits uncovered. If the light source wavelength is 450 nm , the thickness of mica sheet is $\alpha \times 10^{-9} \mathrm{~m}$. The value of $\alpha$ is

$\_\_\_\_$ .