A thin lens focal length `f_(1)` and its aperture has diameter `d`. It forms an image of intensity
Channel: Doubtnut
Date: 2020-01-19

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