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

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 convex lens of focal length f, has its aperture of diameter d. It forms a real iomage of intensity I. The central part of the aperture is blocked by an opaque paper of diameter (d)/(2) . What is the focal length of the lens and the intensity of image formed by the lens ?

A thin lens of focal length f has aperture d . It forms an image of intensity I . Inner part of a lens upto diameter d//2 is painted black, the intensity of the image will be :

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