Question

An object of 2cm in length is held perpendicular to the principal axis at 5cm away from a convergent lens of focal length 2.5cm. Draw the ray diagram​

Answer 1

Given:

An object of 2cm in length is held perpendicular to the principal axis at 5cm away from a convergent lens of focal length 2.5cm.

To draw:

Ray diagram !

Calculation:

Applying Len's Formula:

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

$\sf \implies\dfrac{1}{2.5} = \dfrac{1}{v} - \dfrac{1}{( - 5)}$

$\sf \implies\dfrac{2}{5} = \dfrac{1}{v} + \dfrac{1}{ 5}$

$\sf \implies \dfrac{1}{v} = \dfrac{2}{5} - \dfrac{1}{ 5}$

$\sf \implies \dfrac{1}{v} = \dfrac{(2 - 1)}{5}$

$\sf \implies \dfrac{1}{v} = \dfrac{1}{5}$

$\sf \implies v = 5 \: cm$

So, image will be produced at 5 cm from lens.

• Image will be real, inverted and same size as the object.

• Now, refer to diagram.