Images by Spherical Mirrors MCQs Quiz | Class 10

This quiz is designed for Class X students studying Science (Code 086), specifically Unit III: Natural Phenomena. The topic covered is Images by Spherical Mirrors, focusing on image nature and position for concave and convex mirrors based on ray diagrams. Attempt all 10 multiple-choice questions, then submit to see your score and download a detailed answer PDF.

Understanding Images Formed by Spherical Mirrors

Spherical mirrors are reflective surfaces that are part of a sphere. They are broadly classified into two types: concave and convex mirrors. Understanding how they form images is crucial in the study of optics, especially when dealing with ray diagrams.

Key Terms Related to Spherical Mirrors

  • Pole (P): The centre of the reflecting surface of a spherical mirror.
  • Centre of Curvature (C): The centre of the sphere of which the reflecting surface is a part.
  • Radius of Curvature (R): The radius of the sphere of which the reflecting surface is a part. It is the distance PC.
  • Principal Axis: The straight line passing through the pole and the centre of curvature.
  • Principal Focus (F): The point on the principal axis where rays parallel to the principal axis converge (concave mirror) or appear to diverge from (convex mirror) after reflection.
  • Focal Length (f): The distance between the pole and the principal focus. For spherical mirrors, R = 2f.

Ray Diagrams for Spherical Mirrors

To determine the position, nature, and size of the image formed by a spherical mirror, we usually consider two or three rays from the object. Here are the common rules for drawing ray diagrams:

  1. A ray parallel to the principal axis, after reflection, will pass through the principal focus (F) in the case of a concave mirror or appear to diverge from the principal focus in the case of a convex mirror.
  2. A ray passing through the principal focus of a concave mirror or a ray which is directed towards the principal focus of a convex mirror, after reflection, will emerge parallel to the principal axis.
  3. A ray passing through the centre of curvature (C) of a concave mirror or directed towards the centre of curvature of a convex mirror, after reflection, is reflected back along the same path.
  4. A ray incident obliquely to the principal axis, towards the pole (P) of the mirror, is reflected obliquely, making equal angles with the principal axis.

Image Formation by Concave Mirror

Concave mirrors form both real and virtual images, depending on the object’s position:

Position of the Object Position of the Image Nature of the Image Size of the Image
At infinity At F Real, Inverted Highly Diminished (point-sized)
Beyond C Between F and C Real, Inverted Diminished
At C At C Real, Inverted Same size
Between C and F Beyond C Real, Inverted Magnified
At F At infinity Real, Inverted Highly Magnified
Between F and P Behind the mirror Virtual, Erect Magnified

Image Formation by Convex Mirror

Convex mirrors always form virtual, erect, and diminished images, regardless of the object’s position:

  • Object at infinity: Image is formed at F (behind the mirror), virtual, erect, and highly diminished.
  • Object between infinity and P: Image is formed between P and F (behind the mirror), virtual, erect, and diminished.

Applications of Spherical Mirrors

  • Concave Mirrors: Used in shaving mirrors, dental mirrors, headlights of cars (as reflectors), solar furnaces (to concentrate sunlight), and as reflectors in torches.
  • Convex Mirrors: Used as rear-view mirrors in vehicles (they provide a wider field of view and always form erect images), and as street light reflectors.

Quick Revision Checklist

  • Remember the two types of spherical mirrors: concave (converging) and convex (diverging).
  • Understand the definitions of P, C, F, R, and f.
  • Practice drawing ray diagrams for different object positions for both concave and convex mirrors.
  • Know the nature, position, and size of images formed in each case.
  • Recall the everyday applications of both types of spherical mirrors.

Practice Questions

Test your understanding with these additional practice questions:

  1. A student is performing an experiment using a concave mirror. He places an object at a distance of 30 cm from the mirror. If the focal length of the mirror is 15 cm, where would the image be formed?
    1. At 30 cm from the mirror
    2. At 15 cm from the mirror
    3. At infinity
    4. Behind the mirror
  2. Which of the following mirrors would you use if you wanted to see a magnified image of your face?
    1. Plane mirror
    2. Convex mirror
    3. Concave mirror
    4. Any spherical mirror
  3. A ray of light traveling parallel to the principal axis of a convex mirror, after reflection, appears to:
    1. Pass through its principal focus
    2. Pass through its centre of curvature
    3. Be parallel to the principal axis
    4. Pass through the pole
  4. The image formed by a convex mirror is always:
    1. Real and inverted
    2. Virtual and inverted
    3. Real and erect
    4. Virtual and erect
  5. Where should an object be placed in front of a concave mirror to obtain a real, inverted, and same-sized image?
    1. At the principal focus
    2. At the centre of curvature
    3. Between the principal focus and the pole
    4. Beyond the centre of curvature