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QJEEM17Phf885: JEE Main 2017 Physics - Class 12 JEEM17Phf885 Solution: In an experiment a convex lens of focal length 15 cm is placed…
In an experiment a convex lens of focal length 15 cm is placed coaxially on an optical bench in front of a convex mirror at a distance of 5 cm from it. It is found that an object and its image coincide, if the object is placed at a distance of 20 cm from the lens. The focal length of the convex mirror is :
Multiple Choice Options
- A 27.5 cm
- B 20.0 cm
- C 25.0 cm
- D 30.5 cm
Step-by-Step Verified Solution
The given optical situation is depicted in the following ray diagram:
In this case, the image forms 55 cm behind the convex mirror and then the reflection takes place due to the mirror image that forms at a distance (v) behind the mirror. Now, this image acts as an object for lens and the final image forms at a distance of 20 m from the lens if the focal length of convex mirror is as follows:
cm