Mirror Coverage and Image – Rankers Physics

Reflection by Spherical Mirrors: Practice Problem & Solution

Assertion (A): If one half of a mirror is covered by an opaque material, then only half image of the object is formed. Reason (R): By covering one half of the mirror, focal length of mirror will be halved.  
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

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Reflection by Spherical Mirrors. Understanding the underlying formula is key to arriving at the correct answer below:

Covering half a mirror reduces the intensity of the image but a complete image is still formed. The focal length of a mirror depends only on its radius of curvature, not on the aperture or how much of its surface is exposed.

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Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Assertion (A): A solid glass sphere is placed in air. A light ray enters into the sphere from outside. The ray cannot undergo total internal reflection inside the sphere. Reason (R): The angle of incidence at \(\text{1}^ \ext{st}\) surface cannot be greater than the critical angle for air-glass system.  
2. The refractive index of material of a plano-convex lens, if the radius of curvature of convex surface is \(10\text{ cm}\) and focal length of lens is \(30\text{ cm}\) is
3. A square of side 2 cm is placed at a distance of 30 cm from a concave mirror of focal length 20 cm. The centre of the square is at the axis of the mirror and the plane is perpendicular to the axis. The area enclosed by the image is :
4. Assertion (A): Law of reflection is applicable for all type of mirrors. Reason (R): Rays which are parallel to principal axis are known as paraxial rays.  
5. Assertion (A): For observing a rainbow, sun should be shining in one part of the sky and it is raining in the opposite part of sky, and observer should stand with his back towards raining side. Reason (R): Rainbow appears due to directly reflection of sunlight from water drops of rain.