Start learning →

ISC Class 12 Ray Optics and Optical Instruments — practice questions — page 2

Explore 55 free Ray Optics and Optical Instruments questions in ISC Class 12 Physics. Open each question or exercise to read its content, reference answers and available explanation.

Practise Ray Optics and Optical Instruments with Quill →

Ray Optics and Optical Instruments questions and exercises with answers

Showing questions 31–55 of 55.

The phenomenon by which the apparent position of a star near the horizon appears slightly higher than its actual position is calledRead the answer and worked solution →The power P of a lens of focal length f (in metres) is given byRead the answer and worked solution →Refractive index of water with respect to air is 4/3. The critical angle for a water–air interface is approximatelyRead the answer and worked solution →Light passes from air (n=1) into glass (n=1.5) at an incidence angle of 60°. Using Snell's law, the angle of refraction isRead the answer and worked solution →For a thin prism of small refracting angle A and refractive index n, the deviation δ is approximatelyRead the answer and worked solution →The apparent depth of an object lying at the bottom of a pool of water (n = 4/3) is, in terms of its real depth h,Read the answer and worked solution →A thin prism of refracting angle 5° is made of glass with n = 1.5. The deviation δ of a light ray passing through it is approximatelyRead the answer and worked solution →Two thin convex lenses, each of focal length 20 cm, are placed coaxially 10 cm apart in air. The equivalent focal length of the combination isRead the answer and worked solution →Cartesian sign convention: positive or negative?Read the answer and worked solution →Critical angleRead the answer and worked solution →Lenses in contactRead the answer and worked solution →Order the steps: solve a mirror problemRead the answer and worked solution →Assertion and reasonRead the answer and worked solution →True or false: optical instrumentsRead the answer and worked solution →Which instrument does this belong to?Read the answer and worked solution →A convex lens of focal length 20 cm is placed in contact with a concave lens of focal length 25 cm. The power of the combination (in dioptres) isRead the answer and worked solution →Complete the prism relationRead the answer and worked solution →An astronomical telescope in normal adjustment has an objective of focal length 100 cm and an eyepiece of focal length 5 cm. Its angular magnification isRead the answer and worked solution →Three of these are wrong. Find the one that holds.Read the answer and worked solution →Which quantity is being described?Read the answer and worked solution →Tap every example of total internal reflectionRead the answer and worked solution →NEET · Physics · Refraction & LensesRead the answer and worked solution →Match each formula to what it describesRead the answer and worked solution →A point source of light is placed at the origin in an isotropic medium. The wavefronts associated with the light are:Read the answer and worked solution →The mirror equation relates u, v and f asRead the answer and worked solution →

Worked practice questions

The phenomenon by which the apparent position of a star near the horizon appears slightly higher than its actual position is called

  1. atmospheric refraction
  2. dispersion of sunlight by clouds
  3. diffraction at the atmospheric layers
  4. scattering of light by air molecules
Show answer and solution

Correct answer: A. atmospheric refraction

1. Your syllabus: the Earth's atmosphere has a refractive index that decreases with altitude (denser near the surface, rarer above). 2. Starlight passing from rarer to denser layers BENDS CONTINUOUSLY toward the normal as it descends. 3. By the time it reaches an observer's eye, the apparent direction is slightly HIGHER than the true direction (the eye traces back the final ray's apparent origin). 4. Consequence: stars near the horizon appear elevated; the sun appears above the horizon for several minutes BEFORE actual sunrise and AFTER actual sunset. 5. This is ATMOSPHERIC REFRACTION — distinct from other phenomena. 6. Options B (dispersion) gives the rainbow. Option C (diffraction) is a wave effect — different cause. Option D (scattering) gives blue sky and red sunsets, not apparent position shift. _Source: syllabus Physics Part 2, Ch 9, §9.5 (Refraction at Atmosphere), p. 8._

Open this question →

The power P of a lens of focal length f (in metres) is given by

  1. P = c / f
  2. P = f / 100
  3. P = 1/f
  4. P = f²
Show answer and solution

Correct answer: C. P = 1/f

1. Power of a lens P = 1 / f (with f in metres). 2. Unit: dioptre (D). 1 D = 1 m⁻¹. 3. Convex lenses have P > 0, concave lenses P < 0. _Source: syllabus Physics Part II, Ch 9 §9.5.3_

Open this question →

Refractive index of water with respect to air is 4/3. The critical angle for a water–air interface is approximately

  1. sin⁻¹(4/3)
  2. sin⁻¹(3/4) ≈ 48.6°
  3. 30°
  4. 60°
Show answer and solution

Correct answer: B. sin⁻¹(3/4) ≈ 48.6°

1. For TIR going from water to air: sin θc = n_air / n_water = 1 / (4/3) = 3/4. 2. θc = sin⁻¹(0.75) ≈ 48.6°. 3. (B) is undefined (sin⁻¹ > 1); (C) and (D) ignore the n-ratio. _Source: syllabus Physics Part II, Ch 9 §9.4 + Table 9.1_

Open this question →

How to practise

  1. Choose a Ray Optics and Optical Instruments question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

Put it into practice

Continue with Ray Optics and Optical Instruments practice for ISC Class 12. Read explanations as you go. No signup form needed to start.

Practise Ray Optics and Optical Instruments →

More Physics topics

Moving Charges and MagnetismCurrent ElectricityElectromagnetic Induction & Alternating CurrentSemiconductor ElectronicsElectromagnetic WavesAtoms and NucleiDual Nature of Radiation and MatterElectric Charges and Fields