Question

draw a ray diagram to show the formation of a three times magnified real image, virtual image of an object kept in front of a converging lens mark the position of object F, 2F,Oand position of the image CLEARLY in the diagram

Answer 1

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Answer 2

Explanation:

Given that,

Magnification m = 3

We know that,

The magnification is the defined as,

$m = \dfrac{v}{u}$....(I)

Put the value of m in equation (I)

$\dfrac{v}{u}=3$

$v = 3u$

(I). For real image,

v = positive, u = negative

Using lens formula,

$\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}$

$\dfrac{1}{3u}+\dfrac{1}{u}=\dfrac{1}{f}$

$\dfrac{1}{f}=\dfrac{4}{3u}$

$u =\dfrac{4f}{3}$

Draw the ray diagram

When the object is placed between f and 2f then the image is formed  real, inverted and enlarged.

(II). For real image,

v = negative, u = negative

Using lens formula,

$\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}$

$\dfrac{1}{-3u}+\dfrac{1}{u}=\dfrac{1}{f}$

$\dfrac{1}{f}=\dfrac{2}{3u}$

$u =\dfrac{2f}{3}$

Draw the ray diagram

When the object is placed between the focus and optical center then the image is formed virtual,erect and enlarged.