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Prefix Multipliers for Physics Help

By — McGraw-Hill Professional
Updated on Sep 17, 2011

Introduction to Prefix Multipliers

Sometimes the use of standard units is inconvenient or unwieldy because a particular unit is very large or small compared with the magnitudes of phenomena commonly encountered in real life. We’ve already seen some good examples: the hertz, the farad, and the henry. Scientists use prefix multipliers , which can be attached in front of the words representing units, to express power-of-10 multiples of those units.

In general, the prefix multipliers range in increments of 10 3 , or 3 orders of magnitude, all the way down to 10 −24 (septillionths) and all the way up to 10 24 (septillions). This is a range of 48 orders of magnitude! It’s not easy to think of an illustrative example to demonstrate the hugeness of this ratio. Table 6-1 outlines these prefix multipliers and what they stand for.

Table 6-1 Prefix Multipliers and Their Abbreviations

Units and Constants Prefix Multipliers

Prefix Multipliers Practice Problems

Problem 1

Suppose that you are told that a computer’s microprocessor has a clock frequency of 5 GHz. What is this frequency in hertz?

Solution 1

From Table 6-1 , observe that the gigahertz (GHz) represents 10 9 Hz. Thus 5 GHz is equal to 5 × 10 9 Hz, or 5 billion Hz.

Problem 2

A capacitor is specified as having a value of 0.001 μF. What is this value in farads?

Solution 2

From Table 6-1 , note that μ stands for micro-, or a unit of 10 −6 . Therefore, 0.001 μF is 0.001 microfarad, equivalent to 0.001 × 10 −6 F = 10 −3 × 10 −6 = 10 −9 F. This could be called a nanofarad (1 nF), but for some reason, engineers rarely use the nano- multiplier when speaking or writing about capacitances. Instead, they likely would stick with the 0.001 μF notation; alternatively, they might talk about 10,000 picofarads (pF).

Problem 3

An inductor has a value of 0.1 mH. What is this in microhenrys?

Solution 3

From Table 6-1 , you can see that the prefix multiplier m stands for milli - or 10 −3 . Therefore, 0.1 mH = 0.1 × 10 −3 H = 10 −4 H = 10 2 × 10 −6 H = 100 μH. 

Practice problems of these concepts can be found at: Units And Constants Practice Test

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