Figure shows an object $ AB $ placed in front of two thin coaxial lenses $ 1 $ and $ 2 $ with focal lengths $ 24\, cm $ and $ 9.0 \,cm $ , respectively. The object is $ 6.0\, cm $ from the lens I and the lens separation is $ L = 10\, cm $ . Where does the system of two lenses produce an image of the object $ AB $ ?
For first lens $f_{1}=24.0\,cm$ $u_{1}=6.0\,cm$ To find $v_{1}$ Using lens formula $\frac{1}{v}-\frac{1}{u_{1}}=\frac{1}{f_{1}}$ $\frac{1}{v}=\frac{1}{f_{1}}+\frac{1}{u_{1}}=\frac{1}{24}-\frac{1}{6}$ $\frac{1}{v}=\frac{1-4}{24}=-\frac{3}{24}$ $v=-8\,cm$ $\therefore$ For second lens $u_{2}=-8\,cm+\left(-10\,cm\right)=-18\,cm$ $f_{2}=9\,cm$ Again using lens formula $\frac{1}{v_{2}}-\frac{1}{u_{2}}=\frac{1}{f_{2}}$ $\frac{1}{v}=\frac{1}{f_{2}}+\frac{1}{u_{2}}=\frac{1}{9}-\frac{1}{18}$ $=\frac{2-1}{18}=\frac{1}{18}$ $\Rightarrow v=18\,cm$ $\therefore$ Final image will be formed at $18\, cm$ to the right of second lens
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Top Questions on Ray optics and optical instruments
Optics, deals with the determination of behaviour and the properties of light, along with its interactions with the matter and also with the instruments that are used to detect it.
Ray optics is also known as the geometrical optics and it is a branch of science which describes light propagation.
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