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Assertion: A boconvex lens of focal leng...

Assertion: A boconvex lens of focal length `10 cm` is split into two equal parts by a plane parallel to its principle axis. The focal length o fthe each part will be `20 cm`.
Reason: Focal length does not depend on the radii of curvature of two surfaces.

A

If both assertion and reason are true and reason correct explanation of assertion.

B

If both assertion and reason are true but reason the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Text Solution

Verified by Experts

The correct Answer is:
D
Since, lens is cut into two, equal parts by a plane parallel to its principle axis, so both part still to be biconvex.
Hence, focal length of each part will remain as before i.e., `10 cm`.
Focal length of biconvex lens
`(1)/(f) = (mu - 1) ((1)/(R_(1)) - (1)/(R_(2)))`
where `R_(1)` and `R_(2)` be the radii of curvature of two surfaces.
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Knowledge Check

  • If a symmetrical convex lens of focal length 'f is cut into two parts along the principal axis as shown in the figure, the focal length of each part will be:

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  • A convex lens has a focal length f. It is cut into two parts along the dotted line as shown in figure. Two focal length of each part will be :

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