Notifications
Clear all
Light Reflection and Refraction
1
Posts
2
Users
0
Likes
334
Views
0
11/08/2021 12:54 pm
Topic starter
When an object is placed at a distance of 15 cm from a concave mirror, its image is formed at 10 cm in front of the mirror. Calculate the focal length of the mirror.
1 Answer
0
11/08/2021 1:00 pm
u = -15 cm, v = -10 cm, f = ?
We know that
\(\frac{1}{v}\) + \(\frac{1}{u}\) = \(\frac{1}{f}\)
⇒ \(\frac{1}{-10}\) + \(\frac{1}{-15}\) = \(\frac{1}{f}\)
⇒ \(\frac{1}{f}\) = \(\frac{1}{10}\) - \(\frac{1}{15}\)
⇒ \(\frac{-3 - 2}{30}\) = \(-\frac{5}{30}\)
= \(-\frac{1}{6}\)
f = -6 cm
The focal length of the concave mirror is 6 cm