Question

a concave lens forms the image of an object such that the distance between the object and the image is 10 centimetre and magnification produced is 1 / 4 find the focal length of the lens,?


Plz help....

Answer 1

Hey there! ☺☻☺

$\text{Distance between object and mirror} = 10 \ cm\\Magification = \frac{\text{height of the image}}{\text{height of the object}}=\frac{v}{u}\\\\\\u-v = 10\\v = u - 10\\\\m = \frac{v}{u}=\\\frac{u-10}{u}= \frac{1}{4}\\4u - 40 = 10\\u = -\frac{40}{3}\\\\v = -\frac{10}{3}\\\\Now,Lens \ formula:\\\frac{1}{f}= \frac{3}{-10}-\frac{3}{-40}\\\\\frac{1}{f}= \frac{-9}{40}\\f = \frac{-40}{9}\\\boxed{\boxed{f = -4.4}}$

Hope It Helps You! ☺☻☺

Answer 2

if u cannot understand plz tell me I help u again