# International System of Units (SI) and Decibels

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1. 1. What is the most widely used system of units, both in everyday commerce and in science?
1. International System of Units (SI)
2. 2. Units are divided into what two subsets?
2. Base Units & Prefixes.
3. 3. How many internationally based units are there?
3. Seven.
4. 4. What may be added to units to
produce a multiple of the original unit?
4. Prefixes.
5. 5. The international system of
units consists of a set of _____ together with a set of _____.
5. Units, Prefixes.
6. 6. Hertz equates to ___________.
6. Frequency.
7. 7. Watt equates to _____.
7. Power.
8. 8. Volt equates to _________ _________.
8. Electrical Potential.
9. 9. Ohm equates to ___________.
9. Resistence.
10. 10. What are the seven base units?
10. Tetra, Giga, Mega, Kilo, Cent, Milli, Micro.
11. 11. What type of sheets uses the decibal unit of measure?
11. Equipment specification sheets.
12. 12. What documents is used when discussing jamming effectiveness?
12. Eloctronic Warfare Documents.
13. 13. What is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power) relative to a specified or implied reference level?
13. Decibal (dB).
14. 14. Decibals is named after who?
14. Alexander Graham Bell.
15. 15. To express the ratio of two power levels P1 and P2 in dB, use the following conversion formula:
15. dB=(P1/P2)log x 10
16. 16. Who uses decibels to deal with large quantities that would be cumbersome to work with?
16. Engineers.
17. 17. If a decibel value is ________, the underlying ratio is greater than one. If it is ________, the ratio is less than one.
17. Positive, Negative.
18. 18. Effective jamming requires how much of a decibal difference?
18. 3 dB.
19. 19. Decibels can also be used with values that are what?
19. Absolute.
20. 20. Decibals express a ratio of what?
20. Two power levels.
21. 21. What is used as a way to express a ratio between two different power levels?
21. Decibals.
 Author: salvadominican ID: 208773 Card Set: International System of Units (SI) and Decibels Updated: 2013-03-25 17:15:39 Tags: International System Units SI Decibels Folders: Description: International System of Units (SI) and Decibels Show Answers: