NCERT Exemplar Class 12

(a) For the telescope described what is the separation between the objective lens and eye piece ? (b) If this telescope is used to view a 100m tall tower 3km away, what is the height of the image of the tower formed by the objective lens ? (c ) What is the height of the [...]

A small telescope has an objective lens of focal length 140cm and eye piece of focal length 5.0cm. What is the magnifying power of telescope for viewing distant objects when (a) the telescope is in normal adjustment (i.e. when the image is at infinity) (b) the final image is formed at the least distance of [...]

An angular magnification (magnifying power) of 30 X is desired using an objective of focal length 1.25 cm and an eye piece of focal length 5 cm. How will you set up the compound microscope ? An angular magnification (magnifying power) of 30 X is desired using an objective of focal length 1.25 cm and [...]

(i) At what distance should the lens be held from the card sheet in order to view the squares distinctly with the maximum possible magnifying power ? (ii) What is the magnification in this case ? (iii) Is the magnification equal to magnifying power in this case ? Explain. A screen is placed 90 cm [...]

A cardsheet divided into squares each of size 1mm2 is being viewed at a distance of 9cm through a magnifying glass (a converging lens of focal length 10cm) held close to the eye. (a) What is the magnification produced by the lens ? How much is the area of each square to the virtual image [...]

A myopia person has been using spectacles of power −1.0 dioptre for distant vision. During old age, he also needs to use separate reading glasses of power +2.0 dioptre. Explain what may have happened. A myopia person has been using spectacles of power −1.0 dioptre for distant vision. During old age he also needs to [...]

Does short-sightedness (myopia) or long-sightedness (hypermetropia) imply necessarily that the eye has partially lost its ability of accommodation? If not, what might cause these defects of vision? Does short-sightedness (myopia) or long-sightedness (hypermetropia) imply necessarily that the eye has partially lost its ability of accommodation? If not what might cause these defects of vision? November [...]

For a normal eye, the far point is at infinity and the near point of distinct vision is about 25cm in front of the eye. The cornea of the provides a converging power of about 40dioptre and the least converging power of eye lens behind the cornea is about 20 dioptre. From this rough data, [...]

You are given prism made of crown glass and flint glass with a wide variety of angles. Suggest a combination of prism which will (i) deviate a pencil of white light without much dispersion. (ii) disperse and displace a pencil of white light without much deviation. A screen is placed 90 cm from an object. [...]

A screen is placed 90 cm from an object. The image an object on the screen is formed by a convex lens two different locations separated by 20 cm. Determine the focal length of the lens is A screen is placed 90 cm from an object. The image an object on the screen is formed [...]