Reading passages

 
 
171 
In order to produce commercial records, an original 
record must first made. It is a flat disc, usually made 
of aluminum coated with a soft layer lacquer. As the 
disc is rotated, a sapphire or ruby stylus cuts a 
continue groove in the lacquer cotang. The stylus 
travels around the disc, making impression that 
corresponds to the amplitude and frequency of the 
sou being recorded. When completed, the original 
may be played back to recre; the original recorded 
sound. If the sound produced by the original record 
satisfactory, the original is coated with silver to 
conduct electricity, and th electroplated with nickel. 
When the original is stripped away, a negative the 
original remains, with a raised spiral pattern 
corresponding to the groo\ in the original. The 
negative is called a master matrix. Next, the mas 
matrix is electroplated with nickel to produce a 
positive of the original. T positive is called a mother 
matrix. By electroplating the mother matrix w nickel 
and stripping it away, stampers are produced. 
Stampers are negath of the original record from 
which the final records may be pressed. 
67. What is the purpose of silver in making 
commerical records?
A)
It strips away the original record. 
B)
It cuts a groove in the original record. 
C)
It aids in electroplating the original record. 
D)
It makes an impression on the stamper. 
E) It is very strong. 
68. The mother matrix is a (n) 
.
A)
negative of the original record 
B)
stamper 
C) original record 
D) record made from a master matrix 
E) hard disc 
 
69. Laquer is used to coat the aluminum disc .
A)
because it conducts electricity 
B)
because it can be cut by a stylus 
C)
because it cools quikly 
D)
because it protects the impression in the 
aluminum 
E) because it is vey soft 
The science of meteorology is deals with the study 
of the structure, state, and behavior of the 
atmoshere. The subject may be approached from 
several directions, but the scene cannot be fully 
appreciated from any one vantage point. Various 
views must be integrated to give perspective to the 
whole picture. One may consider the condition of 
the atmosphere at a given moment and attempt to 
predict changes from that condition over a period of 
a few days ahead. This approach is included in the 
branch of the science called synoptic meteorology. 
Synoptic meteorology is the scientific basis of the 
technique of weather forecasting by means of the 
preparation and analysis of weather rrnps and 
aerological diagrams. The practical importance of 
the numerous applications of weather forecasting 
cannot be overestimated. In serving the needs of 
shipping. aviation, agriculture, industry, and many 
other interests and fields of human activity with 
accurate weather warnings and professional forecast 
advice, great benefits are reaped in the form of the 
saving of human life and property and in economic 
advantages of various kinds. One significant purpose 
of the science of meteorology is constantly to strive, 
through advanced study and research, to increase 
bur knowledge of the atmosphere with the aim of 
improving the accuracy of weather forecasts. 
70.