NCERT
- The refractive index of diamond is 2.42. What is the meaning of this statement? The refractive index of diamond is 2.42. This means that the speed of light in diamond will reduce by a factor of 2.42 as compared to its sp... 1
- You are given kerosene, turpentine and water. In which of these does the light travel fastest? In water light travel faster as compare to kerosene and turpentine because the refractive index of water is lower than that of kerosene and... 1
- Find out, from Table, the medium having highest optical density. Also find the medium with lowest optical density. Highest optical density = Diamond Lowest optical density = Air Optical density of a medium is directly related with the refractive index of... 1
- Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? Refractive index of a medium, n_m = Speed of light in vacuum/Speed of light in the medium Speed of light in vacuum, c = 3 × 10⁸ ms⁻¹ Refract... 1
- A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal The ray of light bends towards the normal. When a ray of light enters from an optically rarer medium (having low refractive index) to an opt... 1
- A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. The magnification(m) is given as = -3 (as image is real) object distance(u) = -10 cm image distance (v)=? we know that m= -v/u -3 = -v /-10... 1
- Find the focal length of a convex mirror whose radius of curvature is 32 cm. Radius of curvature, R= 32 cm Radius of curvature = 2 × Focal length (f) R= 2ff= R/2 = 32/2 = 16 Hence, the focal length of the given convex... 1
- Why do we prefer a convex mirror as a rear-view mirror in vehicles? We prefer a convex mirror as a rear-view mirror in vehicles because it gives a wider field of view, which allows the driver to see most of t... 1
- Name the mirror that can give an erect and enlarged image of an object. Concave Mirror 2
- The radius of curvature of a spherical mirror is 20 cm. What is its focal length? Radius of curvature, R= 20 cm Radius of curvature of a spherical mirror = 2 × Focal length (f)R= 2f f= R/2 = 20 / 2 = 10 Hence, the focal le... 1
- Define the principal focus of a concave mirror. Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting f... 1
- Only variations that confer an advantage to an individual organism will survive in a population. We agree with the statement that Only variations that confer an advantage to an individual organism will survive in a population. All the va... 2
- How is the equal genetic contribution of male and female parents ensured in the progeny? In human beings, equal genetic contribution of male and female parents is ensured in the progeny through inheritance of equal number of chro... 1
- Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. Sexual reproduction causes more viable variations due to the following reasons: Error in copying of DNA, which are not highly significant. R... 1
- What evidence do we have for the origin of life from inanimate matter? The evidence for the origin of life from inanimate matter, was provided through an experiment, conducted in 1953, by Stanley L. Miller and H... 1
- Explain the importance of fossils in deciding evolutionary relationships. Fossil provide us evidence about The organisms that lived long ago such as the time period during which they lived, their structure etc. Evo... 1
- Outline a project which aims to find the dominant coat colour in dogs. Dogs have a variety of genes that govern coat colour. There are at least eleven identified gene series (A, B, C, D, E, F, G, M, P, S, T) tha... 1
- Explain the terms analogous and homologous organs with examples. Homologus organs are those organs which have the same basic structural design and origin but have different functions. For Example: The fore... 1
- How are the areas of study - evolution and classification - interlinked? Classification involves grouping of organism into a formal system based on similarities in internal and external structure or evolutionary h... 1
- A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. This information is not sufficient. For considering a trait as dominant or recessive, we need data of at least three generations. This data... 1
- In evolutionary terms, we have more in common with (a) a Chinese school-boy. (b) a chimpanzee. (c) a spider. a) a Chinese school-boy. 2
- An example of homologous organs is (a) our arm and a dog's fore-leg. (b) our teeth and an elephant's tusks. Answer: (d) all of the above Homologous organs have the same basic structure and origin but may perform different functions. Our arm and a d... 1
- A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white Correct option is c) TtWW 2
- In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a 'better' body Evolution cannot always be equated with progress or better body designs. Evolution simply creates more complex body designs. However, this d... 1