Ray Optics and Optical Instruments

32 solved questions from Class 12 Physics, each with the full working. Tap any question to see the step-by-step solution.

• 1 What is the fundamental law or governing principle of 'Ray Optics and Optical Instruments' in Class 12 Physics? medium MCQ Fundamental Physical Law
• 2 What is the SI unit and dimensional formula for the key physical quantity studied in 'Ray Optics and Optical Instruments'? medium MCQ SI Units & Dimensional Analysis
• 3 How does the field or potential intensity vary with distance r in 'Ray Optics and Optical Instruments'? medium MCQ Spatial Distance Dependence
• 4 What is the net flux or circulation integral through a closed surface in 'Ray Optics and Optical Instruments'? medium MCQ Gauss's Theorem & Boundary Integrals
• 5 Why do field lines in 'Ray Optics and Optical Instruments' never intersect each other? medium MCQ Field Line Properties
• 6 A compound microscope uses an objective lens of focal length 4.0 mm and an eyepiece of focal length 25.0 mm. The distance between the lenses (tube length) is 160 mm. Calculate (i) the magnifying power of the objective, (ii) the angular magnification of the eyepiece (assume the final image is formed at the near point 25 cm), and (iii) the overall magnification of the microscope. hard 4 marks Magnification of compound microscope
• 7 Two thin lenses are placed in contact. A convex lens of power +5.0 D and a concave lens of power -2.0 D are used. Find the focal length of the combination in centimeters. medium 2 marks Power of thin lenses in contact
• 8 A thin convex lens has a power of +8.0 D. An object is placed 30 cm in front of the lens. Calculate the image distance v from the lens. State whether the image is real or virtual and upright or inverted. easy 2 marks Lens formula and sign convention
• 9 A person has a relaxed eye (infinite far point) with a focal length of 2.5 cm. The eye can accommodate an additional 20 D of power. Calculate the least distance of distinct vision (near point) for this person, in centimeters. medium 3 marks Accommodation and near point of the eye
• 10 A compound microscope is constructed using an objective lens of focal length f_o = 3.0 mm and an eyepiece of focal length f_e = 20.0 mm. The tube length (distance between the lenses) is L = 160 mm. The final image is formed at the near point of the relaxed eye (D = 25 cm). Calculate (i) the magnifying power of the objective m_o, (ii) the angular magnification of the eyepiece M_e, and (iii) the overall linear magnification M_total of the microscope. hard 5 marks Magnification in a compound microscope
• 11 A refracting telescope consists of an objective lens of focal length f_o = 100 cm and an eyepiece of focal length f_e = 10 cm. The final image is formed at infinity. What is the angular magnification M of the telescope? medium MCQ 3 marks Angular magnification of a refracting telescope
• 12 A compound microscope uses an objective lens of focal length f_o=5.0 mm and an eyepiece of focal length f_e=20.0 mm. The tube length (distance between the lenses) is L=180 mm. The final image is formed at the near point of the relaxed eye (D=25 cm). (i) Determine the object distance u_o from the objective such that the intermediate image formed by the objective lies d_i mm beyond the objective. (ii) Compute the magnifying power of the objective m_o, the angular magnification of the eyepiece M_e, and the overall magnification M_total of the microscope. hard 5 marks Microscope magnification calculation
• 13 Two thin lenses are placed 10 cm apart along the same principal axis. The first lens is convex with focal length f_1=+15 cm and the second lens is concave with focal length f_2=-20 cm. An object is placed 30 cm in front of the first lens. Find the final image distance from the second lens. Choose the correct answer. A) -45 cm B) +55 cm C) -25 cm D) +35 cm medium MCQ 3 marks Combination of separated lenses
• 14 A thin convex lens has a focal length of +25,cm. An object is placed 40 cm in front of the lens. Using the sign convention for lenses, calculate (i) the image distance v, (ii) the nature of the image (real/virtual), and (iii) whether the image is upright or inverted. easy 2 marks Lens formula application
• 15 A refracting telescope has an objective lens of focal length f_o=80 cm and an eyepiece of focal length f_e=8 cm. The telescope is adjusted so that the final image is formed at the near point of a relaxed eye (D=25 cm). (i) Find the angular magnification M of the telescope in this relaxed‑eye configuration. (ii) If the telescope is instead adjusted for viewing distant stars (final image at infinity), what would be the angular magnification? medium 3 marks Telescope angular magnification
• 16 A thin concave lens has a focal length of -20 cm. An object is placed 15 cm in front of the lens. Using the sign convention for lenses, calculate (i) the image distance v, (ii) whether the image is real or virtual, and (iii) whether the image is upright or inverted. easy 2 marks Lens formula for concave lens
• 17 A refracting telescope is adjusted for normal relaxed eye observation (final image at infinity). Its objective lens has focal length f_o=120 cm and its eyepiece has focal length f_e=12 cm. Calculate the angular magnification M of the telescope. medium 2 marks Telescope angular magnification
• 18 A compound microscope uses an objective lens of focal length f_o=4.0 mm and an eyepiece of focal length f_e=25.0 mm. The tube length (distance between the lenses) is L=150 mm. The final image is formed at the near point of a relaxed eye (D=25 cm). Determine (i) the object distance u_o from the objective so that the intermediate image formed by the objective lies d_i mm beyond the objective, (ii) the linear magnification of the objective m_o, (iii) the angular magnification of the eyepiece M_e, and (iv) the overall magnification M_total of the microscope. hard 5 marks Microscope magnification (objective and eyepiece)
• 19 A thin convex lens of focal length +12 cm forms an image of a candle placed 30 cm from the lens. Find (i) the image distance v, (ii) whether the image is real or virtual, (iii) whether it is upright or inverted, and (iv) the linear magnification m. easy 2 marks Lens formula and magnification
• 20 Two thin lenses are placed 8 cm apart on the same principal axis. The first lens is convex with focal length f_1=+10 cm and the second lens is convex with focal length f_2=+20 cm. An object is placed 40 cm in front of the first lens. Find the final image distance measured from the second lens. Choose the correct option. hard MCQ 4 marks Image formation by a system of separated lenses
• 21 A simple magnifying glass (convex lens) has a focal length f=5 cm. The near point of the unaided eye is D=25 cm. (i) Find the angular magnification M_(∞) when the eye is relaxed and the final image is at infinity. (ii) Find the angular magnification M_D when the eye is accommodated so that the final image is at the near point D. hard 5 marks Magnifying power of a simple lens
• 22 A compound microscope has an objective lens of focal length f_o=3 mm and an eyepiece of focal length f_e=20 mm. The tube length (distance between the lenses) is L=150 mm and the final image is formed at the near point of a relaxed eye (D=25 cm). Calculate the overall linear magnification M_total of the microscope. medium 3 marks Overall magnification of a microscope
• 23 A compound microscope has an objective lens of focal length 4.0,mm and an eyepiece of focal length 30.0,mm. The distance between the lenses (tube length) is 140,mm and the final image is formed at the near point of a relaxed eye (D=25,cm). Calculate (i) the linear magnification of the objective, (ii) the angular magnification of the eyepiece, and (iii) the overall linear magnification of the microscope. hard 4 marks Microscope magnification
• 24 A thin convex lens of focal length 18,cm forms an image of an object placed 45,cm from the lens. Find the image distance v (in cm). easy 1 mark Thin lens equation
• 25 A refracting telescope has an objective lens of focal length 90,cm and an eyepiece of focal length 10,cm. The telescope is adjusted so that the final image is formed at the near point of a relaxed eye (D=25,cm). (i) Find the angular magnification M of the telescope in this relaxed‑eye configuration. (ii) If the telescope is instead adjusted for viewing distant stars (final image at infinity), what would be the angular magnification? hard 3 marks Telescope magnification
• 26 A thin convex lens has a focal length of 15,cm and an object is placed 50,cm in front of it. Find the image distance in centimeters and state whether the image is real or virtual. easy 2 marks Thin‑lens formula
• 27 A refracting telescope has an objective lens of focal length 75,cm and an eyepiece lens of focal length 25,cm. The telescope is adjusted so that the final image is formed at the near point of a relaxed eye (D=25,cm). (i) Find the angular magnification M of the telescope in this relaxed‑eye configuration. (ii) If the telescope is instead adjusted for viewing distant stars (final image at infinity), what would be the angular magnification? hard 3 marks Angular magnification of telescope
• 28 A thin convex lens has a focal length of 12,cm and an object is placed 20,cm in front of it. Find the image distance (in cm) and state whether the image is real or virtual. easy 1 mark Thin lens formula and sign convention
• 29 A compound microscope uses an objective lens of focal length 5,mm and an eyepiece lens of focal length 15,mm. The distance between the lenses (tube length) is 120,mm and the final image is formed at the near point of a relaxed eye (D=25,cm). Calculate the overall linear magnification of the microscope. medium 2 marks Microscope magnification calculation
• 30 A refracting telescope has an objective lens of focal length 120,cm and an eyepiece lens of focal length 15,cm. The telescope is adjusted so that the final image is formed at the near point of a relaxed eye (D=25,cm). Calculate the angular magnification M of the telescope in this relaxed‑eye configuration. medium 4 marks Angular magnification of telescope (near‑point adjustment)
• 31 A refracting telescope consists of an objective lens of focal length 120,cm and an eyepiece of focal length 10,cm. The telescope is adjusted so that the final image is at infinity (relaxed eye). What is its angular magnification? hard 3 marks Telescope angular magnification relaxed eye
• 32 A refracting telescope has an objective lens of focal length 150,cm and an eyepiece of focal length 30,cm. It is adjusted for viewing distant stars (final image at infinity). Calculate the angular magnification. medium 3 marks Angular magnification of a telescope