A student wants to project the image of a candle flame on the walls of school laboratory by using a lens:
(a) Which type of lens should be use and why?
(b) At what distance in terms of focal length 'F' of the lens should be place the candle flame so as to get (i) a magnified, and (ii) a diminished image respectively on the wall? Draw ray diagram to show the formation of the image in each case?
a) A convex lens should be used to form a real image.
b) i) In order to get a magnified image, the candle flame should be placed between F and 2F.
ii) The diminished image is obtained when the object is kept at a distance greater than 2F.
c) Ray diagram for the formation of magnified image is,
Ray diagram for the formation of the diminished image is:
(a) List three common refractive defects of vision. Suggest the way of correcting these defects.
(b) About 45 lac people in the developing countries are suffering from corneal blindness. About 30 lac children below the age of 12 years suffering from this defect can be cured by replacing the defective cornea with the cornea of a donated eye. How and why can students of your age involve themselves to create awareness about this fact among people?
