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 upto diameter 
is blocked by an opaque paper. The focal length and image intensity will change to -
A
and 
B
f and 
C
and 
D
f and 
Text Solution
Verified by ExpertsThe correct answer is:
D
I ∝ ∝ A 2 ⇒ 
= 
= 
= 
= 
⇒ I 2 = 
I 1
And focal length remains unchanged.
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