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Physics-Lenses

NEET Physics Lenses Assertion Reason Question

Type: Assertion Reason-assertion-Medium-Class 12

Assertion (A): A combination of a convex lens of focal length 30 cm and a concave lens of focal length 20 cm results in a diverging lens system.

Reason (R): The effective focal length of a combination of lenses is the algebraic sum of their individual focal lengths.

A

Both A and R are true, and R is the correct explanation of A.

B

Both A and R are true, but R is not the correct explanation of A.

C

A is true, but R is false.

D

A is false.

Correct Answer

Option A

Detailed Explanation

The effective focal length of a lens combination is given by the algebraic sum of individual focal lengths (Physics 238, Eq. 9.31). A positive focal length for a convex lens and a negative focal length for a concave lens result in a net negative focal length, making the combination diverging.

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