Question

an object is placed at a distance of 30 cm from a convex lens of focal length 20 cm . find the position of image​

Answer 1

Given :

• Object is placed at a distance of 30 cm from a convex lens.
• Focal length of the lens is 20 cm .

To Find :

• Position of Image .

Solution :

$\longmapsto\tt{Object\:Distance\:(u)=-30\:cm}$

$\longmapsto\tt{Focal\:Length\:(f)=20\:cm}$

Using Formula :

$\longmapsto\tt\boxed{Mirror\:Formula=\dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u}}$

Putting Values :

$\longmapsto\tt{\dfrac{1}{f}+\dfrac{1}{u}=\dfrac{1}{v}}$

$\longmapsto\tt{\dfrac{1}{20}+\dfrac{1}{(-30)}=\dfrac{1}{v}}$

$\longmapsto\tt{\dfrac{1}{20}-\dfrac{1}{30}=\dfrac{1}{v}}$

$\longmapsto\tt{\dfrac{3-2}{60}=\dfrac{1}{v}}$

$\longmapsto\tt{\dfrac{1}{60}=\dfrac{1}{v}}$

$\longmapsto\tt\bf{60\:cm=v}$

So , The Position of the image is 60 cm and the image formed is real and inverted .

Answer 2

★ Question Given :

• ➦ An object is placed at a distance of 30 cm from a convex lens of focal length 20 cm . find the position of image ?

★ Required Solution :

✰ Value Given to us :

• ➣ Object placed at a distance of 30 cm

• ➣ Focal length of lens = 20 cm

✰ Formula Used Here :

• ➨ 1 / f = 1 / v - 1 / u

✰ Putting Value in Formula :

• ➝ 1 / 20 = 1 / v - 1 / 30

• ➝ 1 / v = 1 / 20 - 1 / 30

• ➝ 1 / v = 3 - 2 / 60

• ➝ 1 / v = 1 / 60

• ➝ V = 60 cm

★ Therefore :

• ➦ The position of image is 60 cm

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