question_answer

In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength \[\lambda \] of the light used is \[\text{5896 { }\!\!\mathrm{\AA}\!\!\text{ }}\] and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is \[\text{0}\text{.20 }\!\!{}^\circ\!\!\text{ }\]. To increase the fringe angular width to \[\text{0}\text{.21 }\!\!{}^\circ\!\!\text{ }\] (with same \[\lambda \] and D) the separation between the slits needs to be changed to                                                                                                            [NEET - 2018]

A)  2.1 mm           

B)       1.9 mm

C)  1.8 mm           

D)       1.7 mm