Intensity, I∝A2 ⇒I1I2=[ A1A2]2=πr2πr2−4πr2=43 ⇒I2=43I1 and focal length remains unchanged.
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…
NEET UG 2010 — Physics Optics
2010mcqeasy
A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter 2d in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively
Official previous-year question
Held on 30 Apr 2010 · Verified 9 Jul 2026.
Options
- A
f and 41
- B
43f and 2I
- C
f and 43I
- D
2f and 2I
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