Twinkling of stars is due to atmospheric refraction.' Explain this statement with the help of a diagram and state the reason why planets do not twinkle.

Explain why the planets do not twinkle?

Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

Why do stars twinkle?

"Vegetable oils are hydrogenated by addition reaction". Explain this statement with the help of a chemical equation. Why are animal fats not hydrogenated? Out of vegetable oils and animal fats which one is preferred for cooking and why?

Explain why some planets do not have atmosphere.

(a) A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m . Two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain : (i) Why the student is unable to see distinctly the objects placed beyond 5 m from his eyes. (ii) The type of corrective lens used to restore proper vision and how this defect is corrected by the use of this lens. (b) If in this case, numerical value of focal length of corrective lens is 5 m , find the power of the lens as per the new cartesion sign convention.

How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?

(a) For a ray of light travelling from a denser medium of refractive index n_(1) to a rarer medium of refractive index n_(2) , prove that (n_(2))/(n_(1)) = sin i_(c) , where i_(c) is the critical angle of incidence for the media. (b) Explain with the help of a diagram, how the above principle is used for transmission of video signals using optical fibers.

A person with a myopic eye cannot see clearly the objects placed beyond 1.5 m. Mention two possible reasons due to which this defect may arise. With the help of ray diagrams show: (a) Why is he unable to see clearly the objects placed beyond 1.5 m from his eye, and (b) What should be the type of the corrective lens used to restore proper vision and how this effect is corrected by the use of this lens?