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Class 10, Science, Chapter-9, Lecture-2, Spherical Mirror (Notes)

CHARACTERISTICS OF AN IMAGE FORMED BY A CONCAVE MIRROR:

POSITION OF OBJECT

CHARACTERISTICS OF IMAGE

RAY DIAGRAM

At Infinity

At focus

Real and Inverted

Highly diminished

FIGURE 10.7 (a) OF NCERT TEXT BOOK

Beyond ‘ C ’

Between F and C

Real and Inverted

Diminished

FIGURE 10.7 (b) OF NCERT TEXT BOOK

At ‘ C ’

At C

Real and Inverted

Of Same size

FIGURE 10.7 (c) OF NCERT TEXT BOOK

Between F and C

Beyond C

Real and Inverted

Magnified

FIGURE 10.7 (d) OF NCERT TEXT BOOK

At ‘ F ’

At Infinity

Real and Inverted

Highly magnified

FIGURE 10.7 (e) OF NCERT TEXT BOOK

Between F and P

Behind the mirror

Virtual and Erect

Magnified

FIGURE 10.7 (f) OF NCERT TEXT BOOK

CHARACTERISTICS OF AN IMAGE FORMED BY A CONVEX MIRROR:

POSITION OF OBJECT

CHARACTERISTICS OF IMAGE

RAY DIAGRAM

At Infinity

At focus (behind the mirror)

Virtual and Erect

Highly diminished

FIGURE 10.8 (a) OF NCERT TEXT BOOK

Between Infinity and

the Pole of the mirror

Between F and P (behind the mirror)

Virtual and Erect

Diminished

FIGURE 10.8 (b) OF NCERT TEXT BOOK

USES OF SPHERICAL MIRRORS:

Concave Mirrors:

  1. as reflectors in the headlights of cars.
  2. as the Doctor’s mirror to focus light on the region to be examined.
  3. as shaving mirrors and make-up mirrors.
  4. as radiation collector in solar heating devices.

Convex Mirrors:

  1. as rear-view mirrors or side-mirror of cars, trucks and buses.
  2. as vigilance-mirrors in big shops and stores.

Reasons: 

  1. A convex mirror always produces an erect image.
  2. The surface of a convex mirror is curved outwards which provides a wider field of view.

SIGN CONVENTION FOR SPHERICAL MIRRORS:

  1. Light is incident on the mirror from the left-hand side of the mirror.
  2. All distances are measured from the pole (P).
  3. Distances in the direction of incident ray are taken as positive.
  4. Distances against the direction of incident ray are taken as negative.
  5. Distances measured upward and perpendicular to the principal axis are taken as positive.
  6. Distances measured downward and perpendicular to the principal axis are taken as negative.