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E003B multiples & si units

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• 1. UEENEEE003B
Solve Problems in Single Path DC Circuits
Multiples, Sub Multiples and SI Units
• 2. The Systeme Internationale’ (SI) is the International Metric System
There are 6 Base Units in the SI system
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Base Units
• 3. The six basic units are not sufficient to act for all situations that arise in measurement.
Derived units are used for all non-basic situations.
Most derived units use the three basic units of length, mass and time in various combinations.
.
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SI Derived Units
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SI Derived Units
The units used can be subdivided into three groups:
mechanical, electrical and magnetic
although it must be realised there are many more examples than those listed
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Derived Mechanical Units
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Derived Electrical Units
• 7. In practical cases some SI values are inconveniently large or small, In order to choose values that are convenient to handle, multiples or submultiples are used.
For example, if the resistance of an electrical installation is measured at 15 000 000 ohms, it is more convenient to refer to this value as 15 megohms.
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Multiples And Submultiples
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Multiples and Submultiples
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• 10. Another method of overcoming cumbersome rows of figures is to notate numbers to a value between 1 and 10 multiplied by 10 to some power.
For example, 6 800 000 can be expressed as
6.8 x 106and
1250 as 1.25 x 103
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Scientific Notation
• 11. Given: 1.015 x 10 -8
Answer: 0.00000001015 (8 places to left)
Negative exponent move decimal to the left
Given: 5.024 x 10 -3
Answer: 5,024 (3 places to the right)
Positive exponent move decimal to the right
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Examples:
• 12. Move decimal point to right for positive exponent of 10
Move decimal point to left for negative exponent of 10
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To change from scientific notation to standard form:
• 13. Examples
Express in standard form
1.09 x 10 3
4.22715 x 10 8
3.078 x 10 – 4
9.004 x 10 – 2
5.1874 x 10 2
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Express in correct scientific notation
0.0000568
321
64 960 000
0.07085
61 500