A candle flame of height 3cm is placed at a distance of 3m from a wall. How far from the wall must a concave mirror be placed so that it may form an image of the flame 9cm high on the wall:
Correct answer: C. 450cm
- A. 425cm
- B. 300cm
- C. 450cm
- D. 650cm
Explanation
To solve this problem, we use the mirror formula: 1/f = 1/v + 1/u, where f is the focal length, v is the image distance, and u is the object distance. By substituting the given values and solving for the object distance, we find x = 1.5m. Therefore, the concave mirror should be placed at 4.5m from the wall, which is 450cm, in order to form an image of the candle flame 9cm high on the wall. Option C is correct. Options A, B, and D are incorrect as they do not provide the accurate calculation based on the mirror formula.
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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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