Two thin lenses in contactसंपर्क में रखे दो पतले लेंसTwo thin lenses in contact

NCERT Fig 9.19 · Class 12 Physics · Chapter 9 · interactive diagram

Parts and what they mean

• Lens A (focal length f₁) (लेंस A (फोकस दूरी f₁)) — Alone it would form the image I₁.
• Lens B (focal length f₂) (लेंस B (फोकस दूरी f₂)) — Takes I₁ as a virtual object and forms the final image I.
• Principal axis (मुख्य अक्ष) — Line through the optical centre O and the foci.
• Ray through the combination (संयोजन से गुज़रती किरण) — Thin lenses in contact: their optical centres coincide at P.
• Ray through the combination (संयोजन से गुज़रती किरण) — Both rays meet at I, closer than I₁: the pair is more converging than A alone.
• Where lens A alone would focus (जहाँ अकेला लेंस A फोकस करता) — 1/v₁ − 1/u = 1/f₁.
• Object O (वस्तु O) — Beyond the focus of lens A.
• Intermediate image I₁ (मध्यवर्ती प्रतिबिंब I₁) — Never actually formed — it only helps the calculation.
• Final image I (अंतिम प्रतिबिंब I) — 1/v − 1/u = 1/f₁ + 1/f₂ = 1/f; in power, P = P₁ + P₂.
• Common optical centre P (उभयनिष्ठ प्रकाशिक केंद्र P) — Distances are measured from here.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 9.19. Report a mistake