Question

"
A convex lens has focal length of 50 cm
distance the position and magnification
image for object at 25 cm
​

Answer 1

Answer:

Given:

•  Focal length (f) = 50 cm

•  Object distance (u) = -25cm (sign by convention)

To find :

•    magnification = ?

•      image distance = ?

Solving Question:

first we have to find the image distance using the formula then magnification by v/u

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

Solution:

$\dfrac{1}{v}-\dfrac{1}{-25}=\dfrac{1}{50}\\\\\implies \dfrac{1}{v}=\dfrac{1}{50}-\dfrac{1}{25}\\\\\implies \dfrac{1}{v}=\dfrac{1-2}{50}\: taking L.C.M\\\\\implies \dfrac{1}{v}=\dfrac{-1}{50}\:\implies v = -50cm$

 image distance =  -50cm

Then, magnification = $\dfrac{v}{u}$

⇒ $\dfrac{(-50)}{-25} \\\\\implies \dfrac{50}{25} \implies 2$

Thus magnification = 2

Thus, the image distance = -50cm and magnification = 2