Simple microscope (magnifier)सरल सूक्ष्मदर्शी (आवर्धक लेंस)Simple microscope (magnifier)

NCERT Fig 9.23 · Class 12 Physics · Chapter 9 · interactive diagram

Parts and what they mean

• Converging lens of short focal length (कम फोकस दूरी का अभिसारी लेंस) — Held close to the eye; the object is placed at or just inside its focal length.
• Principal axis (मुख्य अक्ष) —
• Principal axis (मुख्य अक्ष) —
• Principal axis (मुख्य अक्ष) —
• Object (just inside F) (वस्तु (F के ठीक अंदर)) — u ≈ −4.2 cm for f = 5 cm, so that the image is at the near point.
• Virtual, erect, magnified image at D (D पर आभासी, सीधा, आवर्धित प्रतिबिंब) — Linear magnification m = 1 + D/f (image at the near point, v = −D).
• Rays forming the image (प्रतिबिंब बनाने वाली किरणें) — Parallel ray (through F′ after the lens) and the ray through the optical centre; their backward extensions meet at the image.
• Eye close to the lens (लेंस के पास आँख) — Sees the enlarged virtual image.
• Focus F (फोकस F) — Object placed just inside it.
• Near point distance D ≈ 25 cm (निकट बिंदु दूरी D ≈ 25 cm) — Closest distance of comfortable clear vision.
• Object at D (no lens) (D पर वस्तु (लेंस नहीं)) — Largest angle the object can subtend while still seen clearly.
• Naked eye (नंगी आँख) —
• Eye (relaxed) (आँख (शिथिल)) — Parallel rays → relaxed eye, image at infinity.
• θo = h/D (θo = h/D) — Angle subtended by the object at the near point, without a lens.
• Magnifying lens (आवर्धक लेंस) — Object exactly at F.
• Object at F (F पर वस्तु) — Rays emerge parallel; image at infinity.
• θi = h/f (θi = h/f) — Angle subtended by the image. Angular magnification m = θi/θo = D/f — one less than 1 + D/f, but comfortable for a relaxed eye.
• F (F) —

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 9.23. Report a mistake