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Ray Optics and Optical Instruments - ISC Class 12 Physics Questions with Answers, Page 5

122 past-paper questions on Ray Optics and Optical Instruments from ISC Class 12 Physics papers (2027-2018), newest first, in full. Questions 81-100 are on this page, 20 to a page. Tap "Show answer" under a question to see its answer.

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2023 · 2 marks · DrawingOpen: Draw a neat and labelled ray diagram to show the formation of a primary rainbow.

Draw the following.

Draw a neat and labelled ray diagram to show the formation of a primary rainbow.

Draw: ray diagram showing the formation of a primary rainbow

Must show: spherical raindrop, incident sunlight ray, refraction and dispersion at entry, internal reflection at back surface, refraction at exit into viewer's eye, violet and red ray paths with angles

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2023 · 3 marks · DerivationOpen: Obtain Prism formula i.e. prove that Where the terms have their usual meaning.

Derive the following.

Obtain Prism formula i.e. prove that $n = \frac{\sin\left(\frac{A + \delta_m}{2}\right)}{\sin\left(\frac{A}{2}\right)}$ Where the terms have their usual meaning.

Given: Refraction of a monochromatic ray of light through a prism of refracting angle $A$ at minimum deviation $\delta_m$

To show: $n = \frac{\sin\left(\frac{A + \delta_m}{2}\right)}{\sin\left(\frac{A}{2}\right)}$

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2023 · 5 marks · Case basedOpen: Optical instruments are of great utility. They help us in studying very tiny…

Answer the following.

Optical instruments are of great utility. They help us in studying very tiny objects as well as very large heavenly bodies. Scientists have developed microscopes like electron microscopes which aid in studying tiny molecules of matter. They have also devised giant telescopes like Hubble telescope and James Web Space telescope which have enabled us to view distant galaxies hitherto unknown.
(i)[1.0]
Which optical instrument is used to study detailed structure of a virus?
(ii)[1.0]
What is the ability of an instrument to form an enlarged image of an object called?
(iii)[1.0]
Hubble telescope orbits around the earth like a satellite. What is the advantage of such a telescope over a similar one on earth’s surface?
(iv)[2.0]
An astronomical telescope consists of two convex lenses having focal length of $200\text{ cm}$ and $4\text{ cm}$. When it forms final image at infinity, calculate its: (a) Magnifying power (b) Length.

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2022 · 3 marks · DrawingOpen: Draw a ray diagram of a refracting astronomical telescope when final image is…

Draw the following.

Draw a ray diagram of a refracting astronomical telescope when final image is formed at infinity. Also write the expression for its angular magnification (magnifying power).

Draw: Ray diagram of a refracting astronomical telescope with final image formed at infinity

Must show: objective lens and eyepiece lens, parallel rays from a distant object, intermediate real, inverted image at the common focal plane, parallel rays emerging from the eyepiece to form image at infinity

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2020 · 5 marks · DerivationOpen: Derive an expression for refraction at a single (convex) spherical surface…

Answer the following.

(i)[4.0]
Derive an expression for refraction at a single (convex) spherical surface, i.e. a relation between $u$, $v$, $R$, $n_1$ (rarer medium) and $n_2$ (denser medium), where the terms have their usual meaning.

Given: A spherical convex surface separating a rarer medium of refractive index $n_1$ from a denser medium of refractive index $n_2$

To show: $\frac{n_2}{v} - \frac{n_1}{u} = \frac{n_2 - n_1}{R}$

(ii)[1.0]
Name the phenomenon due to which the sun appears reddish at sunset.

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2020 · 1 mark · MCQOpen: In an astronomical telescope of refracting type:

Choose the correct option.

In an astronomical telescope of refracting type:
  • (a)Objective should have small focal length.
  • (b)Objective should have large focal length.
  • (c)Eyepiece should have large focal length.
  • (d)Both objective and eyepiece should have large focal length.

No answer yet.

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