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Why is the ans (1)?

Isn’t the lighter shadow formed by A and not C based on the placement of A, B, C shown? 

Thanks in advance.


Answer has to be (1).

Since A is nearest to the light source, its shadow will be the largest.  Clear glass allows most light to pass through, and will cast a faint shadow on the screen.

B is second nearest to the light source, hence B’s shadow will be smaller than A’s shadow.  The light from the torch passes through the clear glass and is blocked by the opaque sphere which does not allow light to pass through.  This results in a dark circle shadow formed within a larger grey diamond shadow on the screen.

C is the farthest from the light source, hence C’s shadow is the smallest of all 3.  It has been eclipsed by shadows of A and B and does not appear on the screen. 

Btw, the drawing isn’t clear as to whether it is a hollow frosted glass frame or a solid frosted glass block, but we can be sure it will be the smallest based on its placement, and is likely blocked by shadows of A and B.  

(3) is out – If the diamond is made of frosted glass, some light will pass through it, casting a darker and larger shadow on the screen.  The light after passing through the frosted glass is scattered and will not be blocked by B.  Try it at home with a frosted panel like bathroom door.    



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