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.
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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.
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