Notifications
Clear all
Light Reflection and Refraction
1
Posts
2
Users
0
Likes
598
Views
0
20/08/2021 1:12 pm
Topic starter
A concave lens has focal length 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens? Also find the magnification produced by the lens.
1 Answer
0
20/08/2021 1:16 pm
f = -15 cm
v = -10 cm
\(\frac{1}{v}\) - \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{-10}\) - \(\frac{1}{u}\) = \(\frac{1}{-15}\)
\(\frac{1}{u}\) = -\(\frac{1}{10}\) + \(\frac{1}{15}\)
\(\frac{1}{u}\) = \(\frac{-1}{30}\)
u = -30 cm
Object should be placed at a distance of 30 cm on the left side of the lens.
m = \(\frac{v}{u}\) = \(\frac{-10}{-30}\)
= +0.33