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An object is placed first at infinity and then at 20 cm from the object side focal plane of a convex lens the two images thus form are 5 CM apart the focal length of the lens is

Pranay , 8 Years ago
Grade 9
anser 1 Answers
Arun
Dear Pranay
For first case
1/f = 1/v - 1/infinity
f = v
For second case
1/f = 1/(f+5)  -  1/-(f+20)
On solving
f = 10 cm
Regards
Arun (askIITians forum expert)
Last Activity: 8 Years ago
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