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The position of fical image formed by the given lens combination from the third lens will be at a distance of `f_1=+10cm,f_2=-10cm,f_3=+30`A. 15 cmB. infinityC. 45 cmD. 30 cm |
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Answer» Correct Answer - 4 For 1 st lens, `u_(1)=-30,f_(1)=+10,` Formal of lens `=(1)/(v_(1))-(1)/(u_(1))=(1)/(f_(1))` `therefore(1)/((v_(1)))+(1)/(10)=(1)/(10)` or `v_(1)=1` om at `I_(1)` behind the lens. The imgage `I_(1)` serves as virtual object for concave lens. For second lens, which is concave, `u_(2)=(15-5)=10cm.` Image distance from third lens `f_(3)=30 cm.` |
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