STANDARD Physics Lens and Aperture 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, I/2
f, I/4
2f, I/2
2f, I/4
Correct Answer
Detailed Explanation
Covering part of the lens does not change the focal length, but reduces the intensity to half.
Found an issue with this question?
Related Questions
More from
Consider a convex lens used as a simple magnifying glass. If an object is placed at a distance of 5 cm from the lens and the lens has a focal length o...
Assertion (A): The thin lens formula is applicable to both convex and concave lenses for real and virtual images. | Reason (R): The focal points of a ...
Consider a diagram where a parallel beam of light is incident on a concave mirror. The reflected rays converge at a point on the principal axis. What ...