1. Prefixes, Units and Unit Conversion
Chapter 2
Prefixes, Units and Unit Conversion

2. Quick review on exponents
103 = 10x10x10 = 1000  10 x 3
3 x 103 = 3x10x10x10 = 3000
24 = 2x2x2x2=16
106 = 10x10x10x10x10x10 = 1,000,000
10-3 = 1/(103) = 1/1000 = .001
10-6 = 1/(106) = 1/1000,000 =
5 x 10-6 = 5 x 1/(106) = 5x =

3. Scientific Units Parameter Unit Length Mass Time For Electronics
Voltage
Current
Resistance
Meter [m]
Kilogram [kg]
Second [s]
Volt [V]
Amp [A]
Ohm [Ω]

4. Other Units

5. Prefixes How many meters are there in a kilometer?
1000
How many milliseconds are there in a second?
How many bytes are there in a Gigabyte?
1,000,000,000

6. Prefixes (cont.) Kilo, milli, and Giga are all called prefixes.
Can you guess why they call them prefixes?
Because they come before the unit such as millisecond.
Prefixes are used to represent how much of the particular unit is being represented

7. Prefixes we’ll use in Elec50A
Abbrev.
Example
What it means
Scientific Notation
Giga G Gm
x1,000,000,000
x109
Mega M MV
x1,000,000
x106
Kilo k kA
x1,000
x103
Unit Base - S x1
x100
Milli m mg
x.001
x10-3
Micro
 Or u uΩ x
x10-6
Nano n ns x
x10-9
Pico p pA x
x10-12

8. In your book they show other prefixes we won’t use much if at all.

9. Quick Prefix Quiz How seconds are there in a Gs?
1 billion
How many volts in a mV?
.001
How many mV in a volt?
1000
How many amps in a kiloAmp (kA)?

10. Quick Prefix Quiz (cont.)
How small is a nA
1 billionth or A or 10-9
How small is a uΩ?
1 millionth or Ω or 10-6
How big is a pV?
1 trillionth of a volt or V

11. 3 ways to write a number
Regular Way Using Prefixes Scientific Notation
1 million volts 1 thousandth of an amp 1 millionth of an ohm 1 billion grams 5 thousand meters 1 second
1,000,000 V
.001 A Ω
1,000,000,000 g
5000 m
1 s
1MV
1mA
1uΩ
1Gg
5km 1s
1x106 V
1x10-3 A
1x10-6 Ω
1x109 g
5x103 m
1x100 s
Notice that the prefixes take place of the scientific notation and everything else stays the same. Meaning –
k = x103

12. Write the following in scientific notation:
3mV
18kV
43ms
2.1GA
30uA
57ps
3x10-3V
18x103V
43x10-3s
2.1x109A
30x10-6A
57x10-12s

13. Write the following using prefixes
Notice “m” replaced all of “x10-3” and everything else stayed the same
483x10-3A
32x106V
2x10-9A
3.4x10-12s
.350x103Ω
42x10-6V
483mA
32MV
2nA
3.4ps
.350kΩ
42uV
This can be simplified to just 350 Ω

14. More practice problems - Converting regular numbers to scientific notation.
Convert 4578 to scientific notation
Convert to scientific notation
Convert 4.56 to scientific notation
What does 6.4 x 10^0 = ?
4.578 x 103
9x10-5
4.56x100
6.4 x 1 = 6.4
Notice in the above example 9x10-5 cannot be converted to a prefix very easily because there is no prefix for -5. So it is useful to convert this number to one that does have a prefix.
9x10-5 = = = 90 x 10-6 = 90u
What we just did was convert scientific notation to engineering notation!!! (Go ahead and write home)

15. So what is the difference between scientific notation and engineering notation?
In scientific notation there is always only one digit or number in front of the decimal and everything else is behind the decimal.
Ex: 9.54 x 10-5
In Engineering notation the exponent is always a multiple of 3.
Ex: 95.4 x 10-6
Notice -6 is a multiple of 3

16. Notice all prefixes are multiples of 3
Abbrev.
Example
What it means
Scientific Notation
Giga G Gm
x1,000,000,000
x109
Mega M MV
x1,000,000
x106
Kilo k kA
x1,000
x103
Unit Base - S x1
x100
Milli m mg
x.001
x10-3
Micro
 Or u uΩ x
x10-6
Nano n ns x
x10-9
Pico p pA x
x10-12

17. We will be using engineering notation for electronics courses because it is useful in converting to prefixes.
Convert the following to engineering notation and then to its corresponding prefix
.00043A
23x10-2V
67x107s m
= 430 x 10-6A = 430uA
= .23V = 230x10-3V = 230mV
= s = 670x106s = 670Ms
= 7.83x10-9s = 7.83nm

18. Random Video of the Day!

19. Get out your Calulators
First put your calculator in Engineering Notation
Press 2nd F
Press SET UP
Press 1 for FSE (Fixed Scientific Engineering
Press 2 for Engineering Notation
Enter 9 so it shows the most amount of precision
It says ENG on the left side of the screen now.
If you ever want your calculator to show normal looking numbers as answers again, you’ll have to go through this process and press 0 for fixed numbers at the last step.

20. Enter and press =.
Notice it automatically put it into Engineering Notation.
It shows 567E3
E is an abbreviated way of saying “x10^”
567E3 = 567 x103
Now press and press enter
You may need to press the Change button to convert it from a fraction
It shows 400E-9.
Convert this to a prefix
400n!!!!

21. Look on Page 21 of your book
Throughout the text book, anytime we will encounter a new feature using the calculator, it will tell you the buttons to press to perform the particular operation.

22. Convert to a prefix using calculator
4300Ω
.00076s
= 56uV
= 5.43MA
= 4.3kΩ
= 760us

23. Using a Calculator for this stuff 3 ways to enter these numbers
Entering 5.4x103
Just enter 5400
5.4x
is the same thing as “x10^”
Sometimes 5.4x103 can be expressed as 5.4E3.
This is the same thing as 5.4 EXP 3
10x
EXP

24. Converting between units
Many times it is useful to convert from one prefix to another. ie: uA to nA
Convert 43uA to nA
43uA = 43000nA
To do this we will use 2 rules. WRITE THESE DOWN!
If you are going from a larger exponent to a smaller exponent, then you move the decimal to the right
If you are going from a smaller exponent to a larger exponent, then you move the decimal to the left

25. Convert 43 mV into _______uV .043V Convert 14kV into ________MV
- If you are going from a larger exponent to a smaller exponent, then you move the decimal to the right. - If you are going from a smaller exponent to a larger exponent, then you move the decimal to the left 43
Convert 43 mV into _______uV
.043V
Convert 14kV into ________MV
Convert 72GV into _______nV
43.uV = 43uV
.014
72,000,000,000,000,000,000V

26. - If you are going from a larger exponent to a smaller exponent, then you move the decimal to the right. - If you are going from a smaller exponent to a larger exponent, then you move the decimal to the left
Now convert to Engineering Notation 10
10x103A
1.5
1.5x106Ω
1.2
1.2x103Hz
5100
5100 x10-6A
0.04
0.04x10-3A 1
1x103W
1500
1500x10-12F
.15
.15x103V
.25
.25x106W
3700
3700x103Ω

27. Using the table. You have this as a handout
Convert 1 microsecond into ________seconds
Convert nanoseconds into ________microseconds
Convert .4 milliohms into __________ ohms
2.8345
.0004

28. Explaining Handout – This handout may be used on tests, but no writing may be on it.

29. Units Worksheet Lets do together 1, 2, 10, 11, 17, 22
Go ahead and finish the rest of the worksheet on your own. If you don’t finish it in class it is homework.
Its due on Monday