Question

What will happen if lower half of convex lens is painted Black?

Answer 1

The lens produce complete picture of the item. 
Consider any point on the surface of the lens. Cover every one of the segments of the lens with a dark paper leaving a little hover around the point. 
Presently consider an item before the lens, say a far off tree. 
Every one of the beams beginning from a point on the highest point of the tree will frame a cone of beams over this little round region of the lens. These beams in the wake of going through the perspective will shape a picture as per the equation 1/u + 1/v = 1/f (take note of that the recipe does not contain any of the parameters such as the distance across of the lens) 
In this way picture of the purpose of the article is shaped at a separation v from the lens. (Note just a point picture of the purpose of the item is framed.) 
Presently consider a point on the base of the tree. Taking after the same technique said over, a point picture of the purpose of the base of the tree is shaped at v. 
Taking after the same technique we can presume that every one of the purposes of the article structure comparing focuses as picture at a separation v, despite the fact that we have secured vast bit of the lens with dark paper. In this way there is a full picture of the tree as beams from all purposes of the tree f subsequent to going through the little roundabout territory fall on the plane where the picture is shaped. 
The contrast between when there is no scope and when there is scope is the force of the picture will be diminished when it is secured than the power when it was not secured. 
At the point when a large portion of the surface is secured a large portion of the power will be lost in the picture.

Answer 2

Explanation:

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