Untitled presentation (10)physics questions.pdf
- 2. A student obtained a sharp image of a candle flame placed at the distant end of the laboratory table on a screen using a concave mirror to determine its focal length. The teacher suggested him to focus a distant building about 1 km far from the laboratory, for getting more correct value of the focal length. In order to focus the distant building on the same screen the student should slightly move the : (a) mirror away from the screen (b) screen away from the mirror (c) screen towards the mirror (d) screen towards the building
- 3. To determine the approximate focal length of the given convex lens by focusing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always : (a) erect and laterally inverted (b) erect and diminished (c) inverted and diminished (d) virtual, inverted and diminished
- 4. State two positions in which a concave mirror produces a magnified image of a given object. List two differences between the two images. 2 marks
- 5. Draw the following diagram, in which a ray of light is incident on a concave/convex mirror, on your answer sheet. Show the path of this ray, after reflection, in each case. (3 marks)
- 6. Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an observer on the moon? Justify your answer with a reason.
- 7. (a) Define the following terms in the context of spherical mirrors : (i) Pole (ii) Centre of curvature (iii) Principal axis (iv) Principal focus Draw ray diagrams to show the principal focus of a : (i) Concave mirror (ii) Convex mirror (c) Consider the following diagram in which M is a mirror and P is an object and Q is its magnified image formed by the mirror.
- 8. (a) Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus. (b) In the above ray diagram mark the object-distance (u) and the image-distance (v) with their proper signs (+ve or – ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case. (c) Find the power of a convex lens which forms a real, and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.
- 9. (a) Write the function of each of the following parts of human eye : Cornea; iris; crystalline lens; ciliary muscles (b) Millions of people of the developing countries of world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission how would you contribute in this noble cause?
- 10. (i) State the objective of organising such campaigns. (ii) List two arguments which you would give to motivate the people to donate their eyes after death. (iii) List two values which are developed in the persons who actively participate and contribute in such programmes.