Mirror Formula Validity – Rankers Physics
Topic: Ray Optics
Subtopic: Reflection by Spherical Mirrors

Mirror Formula Validity


Assertion (A): The formula \(\frac{1}{v} + \frac{1}{u} = \frac{1}{f}\) connecting u and v for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvatures.
Reason (R): Laws of reflection are strictly valid for smaller size of optical system.
 
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution:

Mirror formula \(\frac{1}{v} + \frac{1}{u} = \frac{1}{f}\) is valid under paraxial approximation, which requires small aperture mirrors. Laws of reflection are fundamental, and their simplified application in the mirror formula relies on paraxial rays. Thus, both (A) and (R) are true, and (R) correctly explains (A).

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