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Prefixes and Conversions in Electrical Measurements

Learn how to convert whole values using prefixes to eliminate zeros. Understand the relationship between prefixes and "whole values." Practice converting and changing between prefixes. Use prefixes in programs for accurate calculations.

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Prefixes and Conversions in Electrical Measurements

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  1. Prefixes and Conversion

  2. Prefixes and Conversions • Prefixes are used to eliminate zeros from a given value. • Conversionschange the numeric value of a measurement from one prefix’s value to another prefix’s value. • “Whole values” are: VOLTS AMPS OHMS FARAD HERTZ (C.P.S.) • “Whole values” have all of the zeros or decimal places in their number value: 3000 volts1000 amps . 5,000,000 ohms. 0.000001 farads • Prefixes are added to “whole value”electrical measurements to eliminate zeros or decimal places: • 3 K volts1 K amps • 5M ohms 1uf

  3. Prefixes and their relationship to “whole values” Prefix Symbol Move decimal pt. Value Mega= 1,000,000 M + 6 places1 M Kilo= 1,000K + 3 places 1 K “whole values” AmpVoltOhmFarad Hertz (C.P.S.) milli= 0.001 m - 3 places 1 m micro= 0.000001 u - 6 places 1 u nano= 0. 000000001 n -9 places 1n pico= 0. 000000000001 p -12 places 1p

  4. Prefixes: Symbol: Mega = + 6 1 M Kilo = + 3 1 K Whole values = 0 milli = - 3 1 m micro = -6 1 u nano = -9 1 n pico = -12 1 p Key to Remember 3 steps You move in steps of 3 between prefixes 3 steps 3 steps 3 steps

  5. Converting from Whole Number Left Prefixes: Symbol: Mega = + 6 1 M Kilo = + 3 1 K Whole values = 0 milli = - 3 1 m micro = -6 1 u nano = -9 1 n pico = -12 1 p Right Which way decimal point moved Moving decimal point left Convert the following: 5,000,000.0 ohms • Determine how many decimal places to move from decimal point to achieve desired value (in this case 5_) • 6 • 2. Which way would I move the decimal point to change the number ? • Left • 3. What prefix will be used? • M • 4. Move the decimal to produce the correct answer. 5,000,000.0 = 5 M ohms

  6. Examples for class to work out • Convert the following whole numbers to the appropriate prefix which minimizes the number of zeros. • 25,000,000 = ___ 256,000 = ____ • 12,000 = ___ 3,100,000 = ___ • 1,000 = ___ 780,000,000 = ___ • 900 = ____ 1,020,000 = ___ ____

  7. Left Prefixes: Symbol: Mega = + 6 1 M Kilo = + 3 1 K Whole values = 0 milli = - 3 1 m micro = -6 1 u nano = -9 1 n pico = -12 1 p Right Which way decimal point moved Move decimal point right Converting from Whole Number Convert the following: 0.000001 f • Determine how many decimal places to move from decimal point to achieve desired value (in this case 1_) • 6 • 2. Which way would I move the decimal point to change the number ? • Right • 3. What prefix will be used? • u • 4. Move the decimal to produce the correct answer. 0.000001 f = 1 uf

  8. Examples for class to work out • Convert the following whole numbers to the appropriate prefix which minimizes the number of zeros. • 0.001 = ____ 0.00001 = ____ • 0.07 = ____ 0.000000002 = ___ • 0.000000000010 = ___ 0.000000025 = ___ • 0.0000047 = ____ 0.0000000039 = ___

  9. Changing between Prefixes • Sometimes it is desired to change between prefixes. For example: • 0.5M to 500K • 1.2nF to 1200pF • 10000nf to 0.01uf • Why? • ½ million sounds bigger than 500K. • Standard way to specify capacitors is in pF • Meters read easier with fewer numbers.

  10. 6pl Prefix to Prefix Conversion Decimal Point • Converting from one prefix to another • Using the scale above, circle the prefix that matches the number you are starting with. • Circle the prefix you want to convert to. • Count the tick marks between the two circles to determine the number of decimal places to move. • Move the decimal point in the same direction as moving from the first circle to second circle and change the prefix letter. Convert 1200p to _u 0.00 1200p = 0.0012u

  11. Problems to work in class • Perform the following prefix to prefix conversions. • 1000p = _____u 120p = ____u • 0.1u = ______n 0.01u =______p • 1n = _______ p 4700p =_____n • 100m = _____K 1100K = _____M • 4M = _____K 3G = ____M

  12. Using Prefixes in Programs • Prefixes can be used in calculators and Excel. • In a Calculator, you usually have a button labeled EE or in Excel you enter “e” to represent 10 to some power. The table below are cross references on what you would enter. • No prefix Prefix Calculator Excel • 1,000,000 1M 1 EE 6 1 e 6 • 1,000 1K 1 EE 3 1 e 3 • 0.001 1m 1 EE -3 1 e –3 • 0.000001 1u 1 EE –6 1 e –6 • 0.000000001 1n 1 EE –9 1 e –9 • 0.000000000001 1p 1 EE-12 1 e –12 • Note that the number to the right of “EE’ or “e” represents how many places to move the decimal point and which way to move. A positive number mean move the decimal point to the left. A negative number means move the decimal number to the right.

  13. How Prefix is applied • Meters are limited in number of digits it can display. • Prefixes are built into the meter. • The numbers on the meter show the maximum value. • If 200uA is selected, the maximum reading is 199uA • If 1 is displayed on 200u A scale, what does this mean? • 1uA or 0.000001A

  14. Meter Problems Convert the following meter readings to whole numbers Meter Scale Reading Whole Number 200m 20 ____________ 200u 36 ____________ 200K 27 ____________ 20K 5.6 ____________ 2000 10 ____________ 20m 16 ____________

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