Unpolarised light is is incident from air on a plane surface of a material of refractive index . At a particular angle of incidence 'i', it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation ?
In Young's double slit experiment the separation
d between the slits is 2 mm, the wavelength of the light used is 5896 and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same and D) the separation between the slits needs to be changed to
An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of