In a Young's double slit experiment, the fringe width is found to be `0.4mm`. If the whole apparatus is immersed in water of refractive index `4//3` without disturbing the geometrical arrangement, the new fringe width will be

Options

A. 0.30 mm
B. 0.40 mm
C. 0.53 mm
D. 450 micron

Answer

A

Explanation

`beta_("water")= (beta_("air"))/(mu)= (0.4)/(4//3)= 0.3 mm`