A lens haivng focal length 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

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 od intensity I, Aperture of diameter d//2 in central region of lens is covered by a block paper. Focal length of lens intensity of image now will be respectively :

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

A thin lens focal length f and its aperture has diameter d . It forms an image of intensity I . Now the central part of the aperture up to diameter (d)/(2) is blocked by an opaque paper. The focal length and image intensity will change to

A thin lens focal length f_(1) and its aperture has diameter d . It forms an image of intensity I . Now the central part of the aperture up to diameter (d)/(2) is blocked by an opaque paper. The focal length and image intensity will change to