A divergent lens has a focal length of 20 cm. At what distance should ...
Answer:
Given:
Focal length of divergent lens, f = -20 cm
Height of object, h = 4 cm
Image distance, v = 10 cm
To Find:
Distance of object from the lens, u
Size of the image, h'
Calculation:
Using lens formula,
1/f = 1/v - 1/u
Substituting the given values,
1/-20 = 1/10 - 1/u
1/u = 1/10 - (-1/20)
1/u = 3/20
u = 20/3 cm
The distance of the object from the lens is 20/3 cm.
The magnification produced by the lens is given by,
m = -v/u
Substituting the given values,
m = -10/(20/3)
m = -3/2
The negative sign indicates that the image is formed on the same side as the object and it is diminished.
The size of the image is given by,
h' = m × h
Substituting the given values,
h' = (-3/2) × 4
h' = -6 cm
The size of the image is -6 cm.
Ray Diagram:
The ray diagram for the formation of the image is shown below:
https://www.edurev.in/api/img/ray-diagram-for-divergent-lens-4_1634137205.png" />
The object is placed beyond the 2F point of the divergent lens. The rays of light coming from the object diverge after passing through the lens. The extended rays intersect at a point on the same side of the lens as the object. This point is the location of the virtual image. The image is formed smaller than the object and is located closer to the lens than the object.