Question
An object is placed at a distance of 30 cm from the lens. Its image is formed at a distance of 10 cm on the same side of the lens. Find the focal length of the lens used.
Answer: Option D
:
D
Given:
Image distance v=−10cm
Object distance u=−30cm
(Using the sign conventions)
Let focal length of the lens be f.
Using the lens formula,
1f=1v−1u
1f=(1−10)−(1−30)
f=−15cm
Here, negative sign for focal length shows that the lens is concave.
Was this answer helpful ?
:
D
Given:
Image distance v=−10cm
Object distance u=−30cm
(Using the sign conventions)
Let focal length of the lens be f.
Using the lens formula,
1f=1v−1u
1f=(1−10)−(1−30)
f=−15cm
Here, negative sign for focal length shows that the lens is concave.
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution