182 ELEMENTARY GENERAL SCIENCE CHAP. 



QUESTIONS ON CHAPTER XI. 



1. How could you show that light travels in straight lines? 



2. Describe experiments to illustrate the characteristics of trans- 

 verse and longitudinal waves. 



3. State the laws of the reflection of light. 



4. In what direction is a beam of light deviated when it passes 

 from a less dense to a more dense medium ? 



5. Name some common phenomena produced by the refraction of 

 light. 



6. Draw a triangle to represent a section of a prism and show how 

 a beam of light is bent by passing through the prism. 



7. State how light can be experimentally analysed by a prism. 



8. How would you prove that white light is composed of several 

 colours, and how can these colours be combined by experiment to 

 form white light ? 



9. Explain the statement ' ' Light is a form of energy. " 



10. Describe a simple experiment to prove the laws of reflection. 



11. What experiment could you perform to explain such every- 

 day phenomena as the shallow appearance of a brook, and the 

 apparent bending of a stick which is slantingly plunged into 

 water ? 



12. Explain the terms principal focus and radius of curvature as 

 applied to a spherical mirror. 



13. Describe some commonly observed effects of the refraction of 

 light. 



14. What is meant by the Dispersion of Light ? On what fact 

 does it depend ? 



15. Explain the term refrangiUlity as applied to a ray of light. 

 Are rays of all colours equally refrangible ? 



16. A bright bead is placed at the bottom of a basin of water, 

 and a person stands in such a position that he can see it over the 

 edge of the basin. While he is looking, the water is drawn off. 

 How will this affect his view ? Draw a diagram showing the direction 

 of a ray of light passing from the bead through the water and the 

 air in each case. 



17. How can it be proved that : 



(a) White light is a mixture of many colours, (b) Different colours 

 have different degrees of refrangibility. 



18. A room is lighted by one small window which can be completely 

 covered by a screen of dark red glass, or by one of blue glass, or 

 by both put together. In the room is a stick of sealing-wax, a piece 

 of blue ribbon and a lily. What colour does each of these things 

 appear when (a) the red screen covers the window, (b) the blue screen 

 covers the window, (c) when both screens cover the window ? 



19. Explain why if a sheet of paper be placed behind a pin-hole 

 in a thick sheet of cardboard, an image of a brilliantly illuminated 

 object on the other side of the cardboard will be formed on the paper. 

 Why is the image fainter, but more clearly defined if the pin-hole is 

 very small ? 



