AIPMT PRELIMS 2010 Physics Lenses MCQ Question
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 by a black paper. Focal length of lens and intensity of image now will be respectively
f/2 and I/2
f and I/4
3f/4 and I/2
f and 3I/4
Correct Answer
Detailed Explanation
Covering the central region of the lens does not change the focal length, but reduces the intensity of the image to 3/4 of its original value.
Found an issue with this question?
Related Questions
More from 2010
Consider the following four statements (a–d) regarding kidney transplant and select the two correct ones out of these. a. Even if a kidney transplant...
Which one of the following statements is correct with respect to AIDS?
The phosphate of a metal has the formula MHPO₄. The formula of its chloride would be