Question

find the distance between two possible positions of a real object in front of a convex lens of focal length 20 cm such that the size of image is triple the size of object
50/3 cm
40/3cm
80/3cm
40cm
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Answer 1

Answer:

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Answer 2

Given: Convex lens of focal length 20 cm.

To find: The distance between two possible positions of a real object

Solution:

• Now we have given convex lens of focal length 20 cm such that the size of image is triple the size of object.

• So magnification of the lens = - 3 ( real object)

• So the magnification of lens is given as = f/f+u = m

• Let u = - u1

• So putting the values in it, we get:

                  -3 = 20/ 20-u1

                  -60 + 3u1 = 20

                  u1 = 80/3 cm

Answer:

           The distance between the position of a real object is 80/3 cm