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A small piece of wire bent into an L shape, with upright and horizontal portions of equal lengths, is placed with the horizontal portion along the axis of the concave mirror whose radius of curvature is 10cm. I fthe bend is 20cm from the pole of the mirror, then the ration of the lengths of the images of the upright and horizontal portions of the wire isA. `1:2`B. `3:1`C. `1:3`D. `2:1` |
Answer» Correct Answer - b. For upright portion, `m=(f)/(f-u)=((-10)/(2))/((-10)/(2)-(-20))=(-5)/(-5+20)=(-5)/(15)=-(1)/(3)` For horizontal portion, magnification is `(-(1)/(3))^(2)` i.e., `(1)/(9)` Required ration is `(-1//3)/(1//9)=-3:1` |
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