An object is placed at a distance of 6cm from a lens that has focal length of 4 cm where is the image located:
Correct answer: B. 12 cm
- A. 10 cm
- B. 12 cm
- C. 14 cm
- D. 16 cm
Explanation
We know the formula 1/f = 1/v - 1/u, where f = focal length of lens, v = distance of image from lens & u = distance of object from lens Rearranging the equation we get, 1/v = 1/f + 1/u We're given that f = 4cm and u = -6cm (-6 since the object is on the left of the lens and the image will form on the right). Plugging in the values we get 1/v = ¼ - ⅙ 1/v = 1/12 v = 12 cm Therefore, B is the correct answer.
This question appeared on the ETEA MDCAT 2005 paper, which you can sit online with every answer explained.
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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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