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.A biconvex lens of focal length 20 cm is cut out into two plano-convex lenses. The focal length of each part is a) 10 cm b) 20 cm c) 30 cm d) 40 cm

.A biconvex lens of focal length 20 cm is cut out into two plano-convex lenses. The focal length of each part is a) 10 cm b) 20 cm c) 30 cm d) 40 cm

Grade:upto college level

2 Answers

Saurabh Koranglekar
askIITians Faculty 10335 Points
2 years ago
Dear student

The focal legth of each part is doubled ie 40cm

Regards
Vikas TU
14149 Points
2 years ago
f = 20 
p = 100/f = 5D 
P1 = P2 = 2.5 D 
Power of combination = 2.5 + 2.5 = 5D 
f = 100/5 = 20cm …...................

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