Virtual images: concave (object inside F) and convex mirrorआभासी प्रतिबिंब: अवतल (वस्तु F के अंदर) और उत्तल दर्पणVirtual images: concave (object inside F) and convex mirror
NCERT Fig 9.6 · Class 12 Physics · Chapter 9 · interactive diagram
Parts and what they mean
- Concave mirror (अवतल दर्पण) — A reflecting surface that is part of a hollow sphere, silvered on the outside so it reflects from the inside (curved in towards the object). Converging.
- Convex mirror (उत्तल दर्पण) — Bulges towards the object; always gives a virtual, erect, diminished image (used as a car side/rear-view mirror).
- Principal axis (मुख्य अक्ष) — The line through the pole P and the centre of curvature C.
- Pole P (ध्रुव P) — Geometric centre of the mirror surface. All distances are measured from P.
- Principal focus F (मुख्य फोकस F) — Rays parallel to the axis meet here after reflection (concave) or seem to come from here (convex). PF = f = R/2.
- Centre of curvature C (वक्रता केंद्र C) — Centre of the sphere of which the mirror is a part. PC = R. A ray through C hits the mirror along the normal and retraces its path.
- Object AB (वस्तु AB) — Height h is positive (above the axis). Object distance u is negative (it is opposite to the incident light, on the left).
- Ray parallel to the axis (अक्ष के समांतर किरण) — Reflects through F (concave). Its backward extension (dashed) goes to the image.
- Ray along the normal (from C) (अभिलंब के अनुदिश किरण (C से)) — Lies on the line from C, so it returns along itself; extended behind the mirror it meets the other extension at A′.
- Ray parallel to the axis (अक्ष के समांतर किरण) — Reflects as if coming from F behind the convex mirror.
- Ray aimed at C (C की ओर जाती किरण) — Hits the mirror normally and comes straight back.
- Virtual image (concave) (आभासी प्रतिबिंब (अवतल)) — Behind the mirror: v positive, m positive (erect), |m| > 1 — the shaving / make-up mirror case.
- Virtual image (convex) (आभासी प्रतिबिंब (उत्तल)) — Between P and F behind the mirror: v positive, 0 < m < 1.
Original diagram drawn by Simple Learning Hub, based on NCERT Fig 9.6. Report a mistake