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To find index error `e` distance between object needle and poler of the concave mirror is `20 cm`. The separation between the indices of object needle and mirror was observed to be `20.2 cm` in some observation, the observed image distance is `20.2 cm` and the object distance is `30.2 cm` find (a) the index error e. (b) focal length of the mirror `f`. |
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Answer» Correct Answer - A::B::C (a) index error e =observed distance - actual distance. = separation between indices- distance between object needle and pole of the mirror `20.0- 20.0= 0.2 cm` (b) `|u|= 30.2 -0.2=30 cm` `:. u =-30 cm` `|v| = 20.2 -0.2=20 cm` `:. v = - 20 cm` Using the mirror formula, `1/f=1/v+1/u=1/(-20)+1/(-30)` or `f =-12 cm`. |
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