Question

किसी 20 सेंटीमीटर फोकस दूरी के उत्तल लेंस के संपर्क में रखे 30 सेंटीमीटर फोकस दूरी के avatal लेंस के संयोजन से बने सयुक्त लेंस ki focus Duri kya hai kya​

Answer 1

Explanation:

A composite lens formed by a combination of a concave lens of 30 cm focus distance placed in contact with a convex lens of 20 cm focus distance . Is this combination convergent or a divergent lens.

• So Focal length of concave lens F1 = - 30 cm
• Focal length of convex lens F2 = 20 cm
• So we have  
•       1/F = 1/F1 + 1/F2
•            = 1/- 30 + 1/20
•          1/F  = 1/60
•   1/F / F1
•      = 1/60 /- 30
•     = - ½
•     = - 0.5
• 1/F / F2
•     = 1/60 / 20
•     = 1/3
•    = 0.33
• Power = 1/p1 + 1/p2  
•            = - 1/0.5 + 1/0.33
•           = 0.17 / 0.165
•            = 1.03
• So power is 1.03
• So the combined lens is positive and hence it is convergent.

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https://brainly.in/question/41250508