150 Common Science 



Inference Exercise 

 Explain the following : 



211. Cut glass ware sparkles. 



212. An unpainted floor becomes much dirtier and is harder to 



clean than a painted one. 



213. If you sprinkle wet tea leaves on a rug before sweeping it, 



not so much dust will be raised. 



214. Food leaves a spoon when the spoon is struck sharply upon 



the edge of a stewpan. 



215. An image is formed on the photographic plate of a camera. 



216. Ripples in a pool distort the image seen in it. 



217. Cream rises to the top of a bottle of milk. 



218. Your eyes have to adjust themselves differently to see things 



near by and to see things at a distance. 



219. A vacuum cleaner does not wear out a carpet nearly as 



quickly as a broom or a carpet sweeper does. 



220. You can see a sunbeam in a dusty room. 



SECTION 25. Magnification. 



Why is it that things look bigger under a magnifying glass 

 than under other kinds of glass? 



How does a telescope show you the moon, stars, and 

 planets ? 



How does a microscope make things look larger? 



Everybody knows, of course, that a convex lens in 

 the right position makes things look larger. People 

 use convex lenses to make print look larger when they 

 read, and for that reason such lenses are often called 

 reading glasses. For practical purposes it is not neces- 

 sary to understand how a convex lens magnifies; the 

 important thing is the fact that it does magnify. But 

 you may be curious to know just how a magnifying 

 glass works. 



First, you should realize that the image formed by a 

 convex lens is not always larger than the object. Repeat 



