JEE Challenger
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Validity of Spherical Mirror Formula and Laws of Reflection

STATEMENT-1
The formula connecting u,vu, v and ff for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvature.

because

STATEMENT-2
Laws of reflection are strictly valid for plane surfaces, but not for large spherical surfaces.

Options

A

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1

B

Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1

C

Statement-1 is True, Statement-2 is False

Correct
D

Statement-1 is False, Statement-2 is True

Step-by-Step Solution

To determine the correct option, let us analyze both statements individually based on the principles of geometrical optics.

Analysis of Statement-1:

The spherical mirror formula is given by:
1v+1u=1f\frac{1}{v} + \frac{1}{u} = \frac{1}{f}

This formula is derived under the paraxial ray approximation, which assumes that:

  1. All rays make very small angles with the principal axis (sin⁡θ≈tan⁡θ≈θ\sin\theta \approx \tan\theta \approx \theta).
  2. The aperture (linear size) of the mirror is very small compared to its radius of curvature RR.

For a spherical mirror with a large aperture, marginal rays (rays striking near the edges) and paraxial rays (rays striking near the pole) do not converge at a single focal point, leading to an optical defect known as spherical aberration. Therefore, the relation connecting u,v,u, v, and ff holds accurately only for mirrors whose sizes are very small compared to their radii of curvature.

Thus, Statement-1 is True.


Analysis of Statement-2:

The laws of reflection state that:

  1. The incident ray, the reflected ray, and the normal to the reflecting surface at the point of incidence all lie in the same plane.
  2. The angle of incidence ii is equal to the angle of reflection rr (i=ri = r).

These laws are fundamental principles of physics and hold strictly for all reflecting surfaces (whether plane, spherical, cylindrical, small, or large) at any local point of incidence. For a spherical surface, the normal at any point is simply the radius vector connecting that point to the center of curvature CC.

Therefore, the statement claiming that laws of reflection are not valid for large spherical surfaces is incorrect.

Thus, Statement-2 is False.


Conclusion:

  • Statement-1 is True.
  • Statement-2 is False.

Hence, the correct choice is (C).