A convex lens of power 4d and a concave lens of power 2d are placed in contact with each other. An object of size 4cm is placed at a distance of 60cm in front of the lens. Find the position, nature and size of the image formed.
Answers
Answer:
Given that the power of the lens, P= 4D
Therefore the focal length of the lens, f = 1/ 4 =0.25 m = 25 cm
Given that the image distance, v = 40 cm
According to lens formula:
begin mathsize 14px style 1 over straight f equals 1 over straight v minus 1 over straight u straight f space equals space 25 space cm straight v space equals 40 space cm straight u equals space ? 1 over straight u equals 1 over straight v minus 1 over straight f 1 over straight u equals 1 over 40 minus 1 over 25 1 over straight u equals fraction numerator 5 minus 8 over denominator 200 end fraction 1 over straight u equals fraction numerator negative 3 over denominator 200 end fraction straight u space equals negative 200 over 3 straight u equals negative 66.67 space cm end style