A convex lens of focal length 'f' and a concave lens of focal length '2f' are placed in contact. The focal length of the combination is:
Correct answer: B. f2 - f1
- A. (f2 + f1:
- B. f2 - f1
- C. (f1*f1)/(f1 + f2):
- D. (-f1*f2)/(f1 - f2):
Explanation
Explanation: When a convex lens and a concave lens are in contact, their focal lengths subtract. Therefore, the resultant focal length is f2 - f1.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Optics
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
Practise Optics
665 free Optics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 11 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Optics questions
Two convex lenses of equal focal length 'f' are placed in contact; the resultant focal length of the combination is:
If a convex lens of large aperture fails to converge the light rays incident on it to a single point, it is said to suffer from:
Least distance of distinct vision for normal and healthy people:
Final image produced by a compound microscope with respect to the object is:
For normal adjustment, length of astronomical telescope is:
A surfboard moves at a speed of 5 m/s on the crests of a wave. The distance between wave crests is 10 m. What is the frequency of the wave motion: