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CBSE · Class 10 · Science · Light – Reflection and RefractionDefine a concave mirror. Draw a ray diagram to show the formation of a real, inverted, and magnified image by a concave mirror. State the position of the object and the image. Also, write the mirror formula and explain each term involved in it.

Step-by-Step Solution

Definition of a Concave Mirror

\nA spherical mirror whose reflecting surface is curved inwards (facing towards the center of the sphere) is called a concave mirror. Concave mirrors are converging mirrors because they converge parallel rays of light falling on them to a single point called the principal focus.

Image Formation by a Concave Mirror

\nWhen an object is placed between the principal focus ($F$) and the center of curvature ($C$) of a concave mirror, the characteristics of the image formed are as follows:

  • Position of Object: Between focus ($F$) and center of curvature ($C$).
  • Position of Image: Beyond the center of curvature ($C$).
  • Nature of Image: Real and inverted.
  • Size of Image: Magnified (larger than the object).

Ray Diagram Description

\nTo construct the ray diagram:

  1. Draw a principal axis with a concave mirror, marking the pole ($P$), focus ($F$), and center of curvature ($C$).
  2. Place an object $AB$ between $F$ and $C$.
  3. Take a ray parallel to the principal axis from point $B$; after reflection, it passes through the principal focus $F$.
  4. Take a second ray passing through the principal focus $F$; after reflection, it travels parallel to the principal axis.
  5. The two reflected rays intersect beyond $C$ at point $B'$, forming a real and inverted image $A'B'$.

Mirror Formula

\nThe mirror formula relates the object distance ($u$), image distance ($v$), and focal length ($f$) of a spherical mirror. The mathematical expression is: $$\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$|

Explanation of Terms:

  • $f$ (Focal length): The distance between the pole ($P$) and the principal focus ($F$) of the mirror.
  • $v$ (Image distance): The distance of the image from the pole ($P$) of the mirror.
  • $u$ (Object distance): The distance of the object from the pole ($P$) of the mirror. \nThis formula is valid under all conditions for all spherical mirrors, provided New Cartesian Sign Conventions are strictly followed.
💡 Study Guide: This question tests core syllabus concepts from Light – Reflection and Refraction. For formulas, key summaries, and mock exam reference guides, read the full Light – Reflection and Refraction Revision Notes.
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