440 REVIEW. 



47. (a.) Define latent, sensible and specific heat. (&.) What is the 

 latent heat of water and of steam ? 



48. (a.) Explain the several modes of diffusing heat, showing 

 how they differ. (&.) State and explain the relation between the 

 absorbing and radiating powers of any given substance. 



49. (a.) What is thermodynamics? (&.) State the first law of 

 thermodynamics, (c.) What is the mechanical equivalent of heat 

 in kilograrnmeters ? (d.) What does your answer mean ? 



50. (a.) Draw a figure showing the position of the parts of the 

 cylinder and steam-chest when the piston is going up. 



51. (a.) To what temperature would a cannon-ball weighing 

 150 Ibs. and moving 1920 feet a second, raise 2000 Ibs. of water 

 from 32 F., if its motion were suddenly converted into heat ? (6.) 

 Explain the origin and propagation of sound waves. 



52. (a.) Express a temperature of 50 F. in degrees centigrade. 

 (6.) Name and describe the essential parts of a steam-engine in their 

 proper order, (c.) Point out the changes in form of energy from 

 the furnace fire, through a high-pressure engine to the heated axles 

 set in motion thereby. 



53. The mechanical equivalent of heat being 1390 foot-grams, 

 the foot being equal to 30.48cm., and the increment of velocity on 

 the earth being 980cm., find the mechanical equivalent in ergs. 



Ans. 41519856. 



54. (a.) What is the difference between waves of sound and 

 waves of light ? (6.) What is the difference between an atherma- 

 nous and an opaque substance ? (c.) What determines the apparent 

 size of a visible object ? 



55. (a.) If the gun-cotton mentioned in 555 (a.) be rubbed with 

 a little lamp-black, will it be ignited with more or less difficulty ? 

 Why? (&.) What is reflection of light? (c.) How does it differ 

 from refraction of light ? 



56. (a.) How could you show that light is invisible unless it en- 

 ters the eye? (&.) What determines the apparent position of an 

 object? (c.) What is the distinction between real and virtual 

 images ? 



57. (a.) Describe and illustrate a construction for conjugate foci 

 in the case of a concave mirror. (6.) In the case of a convex lens, 

 (c.) What is meant by the index of refraction ? (d.) Give the laws 

 for refraction of light. 



58. (a.) Explain total internal reflection. (&.) What is meant by 

 dispersion of light? (c.) What is pure spectrum and how may it 

 be produced ? (<?.) What are Fraunhofer's Lines and what do they 

 indicate? (e.) Name the prismatic colors in order. 



