If an object be placed at a distance of 60cm from a convex lens of a focal length 20cm, a real image is formed behind the lens. Obtain the position of the image and its magnification.
If an object be placed at a distance of 60cm from a convex lens of a focal length 20cm, a real image is formed behind the lens. Obtain the position of the image and its magnification.
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Given:
An object is placed at a distance of 60 cm from a convex lens of a focal length of 20 cm.
To Find:
The position of the image formed and the lens' magnification.
Formula:
We know that, 1/v + 1/u = 1/f, and magnification = v/u .
Solution:
Object distance (u) = 60 cm
Focal length (f) = 20 cm
1/v + 1/u = 1/f
or, 1/v = 1/f - 1/u
or, 1/v = 1/20 - 1/60
or, 1/v = 1/30
or, v = 30 cm
Magnification = v/u
ᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠ= 30/60
ᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠ= 1/2
Answer:
The image distance is 30 cm, and the magnification by the lens is 1/2 .