Unit: lenses
Year: 1997 Question#: 92
Question: Based your answers to questions 92 and 93 on the information below.
A crown glass converging lens has a focal length of .10 meter.
Which cross-section diagram best represents this lens?
(1 )
(2 )
(3 )
(4 )
What is this question really asking?
Explanation by: Weirui Z.
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Answer 1
INCORRECT
A lens that is thinner in the middle would diverge light rather than converge it. It behaves in this way:
From the diagram it is easy to see that the focal length of the above diverging lens is negative. return to top
Answer 2
INCORRECT
A lens that is thinner in the middle would diverge light rather than converge it. It behaves in this way:
`
From the diagram it apparent that the focal length of the above diverging lens is negative. return to top
Answer 3
INCORRECT
This lens wil not diverge or converge light. It has no focal point. return to top
Answer 4
CORRECT
A converging lens is fatter in the middle than at the edges. The lens will bend light in this way:
This is the only choice with a positive focal length. return to top
What's this question really asking?
How is a converging lens shaped? What kind of lens has a positive focal length?
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