SSC
PHYSICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Focal length of plane mirror is
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At infinity
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Zero
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Negative
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None of these
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Explanation:
Detailed explanation-1: -If parallel rays fall on mirror, then after reflection they are still parallel and these rays appear to meet at infinity so the focal length of a plane mirror is infinity.
Detailed explanation-2: -Focal length of plane surface are infinity as in case of glass slab angle of incidence is equal to angle of emergent with a shift. Hence the rays will meet at infinity which makes their focal length infinity.
Detailed explanation-3: -However the focal length of a plane mirror is infinity; its optical power is zero. Concave and Convex mirrors (spherical mirrors) are also able to produce images similar to a plane mirror.
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