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Radius of curvature of a biconvex lens is 20 cm. An object of 2 cm height is placed at 30 cm from lens, then which option represents the image ? |
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Answer» Virtual, erect, of HEIGHT 1 cm Now `1/f=(mu-1)((1)/(R_1)-(1)/(R_2))` `=(3/2-1)[(1)/(20)-(-(1)/(20))]` `1/f=(3/2-1)XX(2)/(20)` `THEREFORE f=20` cm Also,`1/f=1/v-1/u` `therefore(1)/(20)=1/v+(1)/(30)` `therefore 1/v=(1)/(20)-(1)/(30)` `=(10)/(600)` `therefore v=60` cm `m=(h_1)/(h_0)-v/u` `therefore h_i=v/uxxh_0` `=(60)/(30)xx2` `therefore h_i=-4` cm negative sign represents that the image is inverted |
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