a glass slab of refractive index 1.5 and thickness of 4.5cm is kept close to concave mirror of focal length 20cm so that the face of the slab is perpendicular to the principal axis of the mirror.a point is placed on the principal axis so that its image coimcides with itself. then the distance of the object from the mirror is?
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Answer:
41.5cm
Explanation:
If the glass slab is not interposed, the object is to be placed at the center of curvature of the mirror (at 40cm). When the glass slab is present, the distance of the object is to be increased by the apparent shift t - (t/μ) produced by the slab, so that the ray emerging from the slab appears to come from the center of curvature of the mirror.
Therefore, distance of the object = 40+ 4.5 – (4. 5/1. 5) = 41.5cm
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