Physics, asked by namanrai7398, 8 months ago

The focal length of a convex lens is 25 cm. At what distance
from the optical centre of the lens an object be placed to
obtain a virtual image of twice the size

Answers

Answered by tusharraj77123
13

Answer:

\large\tt\color{pink}\underline{\underline{Question:}}

\textsf{The focal length of a convex lens is 25 cm.}

\textsf{At what distance from the optical center of}

\textsf{of the lens an object be placed to obtain}

\textsf{a virtual image of twice the size}

\large\tt\color{blue}\underline{\underline{Given:}}

\textsf{Length of a convex lens = 25 cm}

\textsf{Size placed obtain a virtual image is twice}

\large\tt\color{green}\underline{\underline{To\:find:}}

\textsf{Distance from the optical center of the lens}

\large\tt\color{cyan}\underline{\underline{We\:know:}}

\bold{Magnification=\frac{Height of the image}{Height of the object}}=2

\textsf{Let Magnification be m}

\textsf{Let height of the image be y}

\textsf{Let height of the object be x}

\large\tt\color{red}\underline{\underline{Solution:}}

\bold{m=\frac{y}{x}=2}

\Rightarrow\bold{\frac{y}{x}=2}

\textsf{Multiply x into 2}

\Rightarrow\bold{y=2x}

\textsf{Use the lens}

\textsf{Let the length of convex lens be f}

\Rightarrow\bold{f=\frac{1}{y}-\frac{1}{x}}

\Rightarrow\bold{\frac{1}{25}=\frac{1}{2x}-\frac{1}{x}}

\Rightarrow\bold{\frac{1}{25}=\frac{1-2}{2x}}

\Rightarrow\bold{\frac{1}{25}=\frac{-1}{2x}}

\Rightarrow\bold{x=\frac{-1}{2}÷\frac{1}{25}}

\Rightarrow\bold{x=\frac{-1}{2}×\frac{25}{1}}

\Rightarrow\bold{x=-12.5cm}

So , the negative sign shows that the image is of the lens ....

HOPE IT HELPS YOU

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