Question

An object is placed at a distance of 20 cm from a diverging lense, the image of the object is formed 10 cm front of the mirror. Find the nature of the image and focal length of the lense.​

Answer 1

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An object is placed at a distance of 20 cm from a diverging lense, the image of the object is formed 10 cm front of the lens . Find the nature of the image and focal length of the lens .

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Given :

• Object Distance (u) = - 20 cm
• Image Distance (v) = 10 cm
• Concave lens

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To Find :

• Focal Length
• Nature of Image

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Solution :

Use lens formula :

$\large{\boxed{\sf{\dfrac{1}{f} \: = \: \dfrac{1}{v} \: - \: \dfrac{1}{u}}}} \\ \\ \implies {\sf{\dfrac{1}{f} \: = \: \dfrac{1}{10} \: - \: \dfrac{-1}{20}}} \\ \\ \implies {\sf{\dfrac{1}{f} \: = \: \dfrac{2 \: + \: 1}{20}}} \\ \\ \implies {\sf{\dfrac{1}{f} \: = \: \dfrac{3}{20}}} \\ \\ \implies {\sf{f \: = \: \dfrac{20}{3}}} \\ \\ \implies {\sf{f \: = \: 6.67}} \\ \\ \underline{\sf{\therefore \: Focal \: length \: is \: 6.67 \: cm}}$

• Nature of Image is Real and Inverted

Answer 2

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