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10 grade science

A plane mirror and a concave mirror of curvature radius 60 cm are placed facing each other, with a point object at the center of them. If the image formed by first reflection at the spherical and then at the plane mirror coincides with the object, then the separation between the two mirrors will

  • A. 40 cm
  • B. 80 cm
  • C. 30 cm
  • D. 60 cm

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10 Months agoGrade
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1 Answer

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ApprovedApproved Tutor Answer10 Months ago

To solve this problem, we need to analyze the behavior of light when it reflects off both a concave mirror and a plane mirror. The key points to consider are the properties of the mirrors and the distances involved.

Understanding Mirror Reflections

A concave mirror converges light rays and can produce real or virtual images depending on the object's position. A plane mirror, on the other hand, always produces a virtual image that is the same distance behind the mirror as the object is in front of it.

Given Data

  • Curvature radius of the concave mirror: 60 cm
  • Object position: Center between the two mirrors

Calculating the Focal Length

The focal length (f) of a concave mirror is given by:

f = -R/2

For a radius (R) of 60 cm, the focal length is:

f = -60 cm / 2 = -30 cm

Image Formation

When the object is placed at the center (30 cm from the concave mirror), the image formed by the concave mirror will be:

Image distance (v) = f = -30 cm

This means the image is formed 30 cm in front of the concave mirror, which is also the same distance from the plane mirror.

Final Image Position

When this image reflects off the plane mirror, it will appear to be 30 cm behind the plane mirror. Therefore, the total distance between the concave mirror and the plane mirror is:

Distance = 30 cm (to the image) + 30 cm (to the plane mirror) = 60 cm

Conclusion

The separation between the two mirrors is therefore 60 cm. Thus, the correct answer is:

D. 60 cm