Question
To determine focal length of a concave mirror a student obtains the image of a well-lit distant object on a screen. To determine the focal length of the given concave mirror he needs to measure the distance between:
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mirror and the object
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mirror and the screen
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screen and the object
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screen and the object and also mirror and the screen
Solution
B.
mirror and the screen
Focal length is the distance between the focus and the mirror. The image of the distant object forms at the focus of the mirror.
