Sahay Sir > Question Answers > NEET Last 32 Years Solved 1988 - 2019 Physics and Chemistry Video Solutions > Physics > Chapter 32 - Ray Optics > A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter d/2​ in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively

A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter d/2​ in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively

In total internal reflection when the angle of incidence is equal to the critical angle for the pair of medium in contact what will be angle of refraction?