In Young's double slit experiment the separation d between the slits is 2 0 mm, the wavelength of light used is 5896A and distance D between the screen and slits is 100cm. It is found that the angular width of the fringes is 0.20°. To increase the angular fringe width to 0.21° (with same A and D) the separation between the slits needs to be changed to.
A. 2.1mm
B. 1.8mm
C. 1.7mm
D. 1.9mm
