Concept explainers
Two thin lenses having focal lengths of +200 cm and –400 cm are glued together so as to have a common axis. Determine the dioptric power of the combination. Discuss the physics of your answer. [Hint: Go back to Eq. (38.4), and then study the definition of dioptric power.]
The dioptric power of the combination of two lenses when the focal length of lensesis
Answer to Problem 14SP
Solution:
Explanation of Solution
Given data:
The focal length of first lens is
The focal length of second lens is
Formula used:
Write the expression for the focal length of the combination of lenses in contact.
Here,
Write the expression for power of the combined lens.
Here,
Explanation:
Recall the expression for the focal length of the combination of lenses in contact.
Substitute
Recall the expression for the power of the combined lens.
Substitute
When the lens of focal length
Conclusion:
The dioptric power of combination of lenses is
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Chapter 39 Solutions
Schaum's Outline of College Physics, Twelfth Edition (Schaum's Outlines)
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