对照翻译
Unit 1 Electric Devices
单元1 电子设备
1.1 Resistors
电阻器
Resistors restrict the flow of electric current. For example，a resistor is placed in ries with a light-emitting diode ( LED) to limit the current passing through the LED.
电阻阻碍电流的流动。例如，一个发光二极管串联一个电阻，以限制通过二极管的电流。
1.1.1 Resistor Values
电阻值
The Resistor Colour Code Resistance is measured in ohm, the symbol for ohm is an omeg
a Ω .1Ωis quite small so resistor values are often given KΩand MΩ
电阻色码 电阻的单位是欧姆，符号是Ω。1Ω很小，电阻值常常用KΩ和MΩ
1KΩ= 1000Ω； 1MΩ= 1000 000Ω.
Resistor values are normally shown using coloured bands. Each colour reprents a number as shown in the Table 1.1.
电阻值通常使用色码带表示。每种颜色代表一个数，如表1.1所示。
Table 1.1 The Resistor Colour Code
表1.1电阻器的颜色代码
Black ，Brown， Red， Orange， Yellow， Green， Blue， Violet， Grey ，White
黑，棕，红，橙，黄，绿，蓝，紫，灰 白recipes
Most resistors have 4 bands:
大多数电阻有4个色环：
The first band gives the first digit.
第一个色环给出阻值第一个数字。
The cond band gives the cond digit.
第二个色环给出阻值第二个数字。
refreshedThe third band indicates the number of zeros.
第三个色环表示零的数目。
The fourth band is ud to show the tolerance (precision) of the resistor,
第四个色环用来表示电阻的精度
学习英语的软件
this may be ignored for almost all circuits but further details are given below.
绝大部分电路都会忽略这一点，但进一步的细节会在后面给出。
The resistor in Figure 1.1 has red (2), violet (7), yellow (4 zeros) and gold bands. So its value is 270 0000=270 kQ. On circuit diagrams the Q is usually omitted and the value is written 270 k.
图1.1中的电阻有红色环、紫色环、黄色环和金色环，这里的amaired (2)指红色代表有效数字第一位数，数值为2， violet (7)指紫色代表有效数字第二位数，数值为7， yellow (4 zeros)指黄色代表倍乘数104所以它的值是270，0000 = 270 KQ。在电路图上，阻值通常省略Ω， 被写成270 K。
scavengersThe standard colour code cannot show values of less than 10 Q. To show the small values two special colours are ud for the third band: gold which means X 0.1 and silver which means X:0.01. The .first and-cond bands: reprent, the. digits as normal.
标准颜色代码不能显示码值小于10的值。要显示这些小于10的值，2个特殊的颜色被用于第三色环：黄金表示乘0.1和银表示乘0.01。第一和第二色环和平常一样。
For example:
例如：
Red, violet, gold bands reprent 27 X 0.1=2.7 Q.
红，紫，金带代表27×0.1 = 2.7。
Blue, green, silver bands reprent 65x0.01=0. 65Q.
蓝色，绿色，银带代表65x0.01 = 0。65q。
Tolerance of Resistors (fourth band of colour code)金融时报中文版 The tolerance of a resistor is shown by the fourth band of the colour code. Tolerance is the precision of the resistor and it is given as a percentage. For example, a 390^resistor with a tolerance of 土 10% _ will have a value within 10% of 39(K2，between 390-3:9=3)1. and 390+39=429 Q (39 is 10% of 390).
电阻误差（第四色环）一个电阻的误差通过第四个色环被表示出来。误差表示电阻的精度，它是作为一个百分比被给出的。例如，一个有±10%的390Ω电阻，它的值将在390Ω的±10%之间，在390-39=351Ω和390 + 39 = 429Ω之间（390的10%是39）。
A special colour code is ud for the fourth band tolerance: silver ± l.O1%，gold ± 5%, red 土 2%，brown ± 1%.
表示误差的第四色环常常用一种特殊的色环表示：银±10 %，金±5%，红±2%，棕±1%。
If no fourth band is shown the tolerance is ± 20%.
如果没有第四个色环，那么误差默认为±20%。
Tolerance may be ignored for almost all circuits becau preci resistor values are rarely required.
几乎所有的电路都会忽略误差，因为精密电阻很少被使用。delivery是什么意思
Resistor Shorthand Resistor values are often written on circuit diagrams using a code system which avoids using a decimal point becau it is easy to miss title small dot. Instead the letters R, K and M a|*e ud in place of the decimal point To read the code: replace the letter with a decimal point,电阻速记。电阻器的电阻值通常是用一个色环代码
系统标注在电路图上，避免使用小数点，因为很容易丢失这个小圆点。反之用字母R，K和M代替小数点。为了读取电阻值，用小数点代替字母，
then multiply the value by 1 000if the letter is K, or 1 000 000 if the letter is M. The letter R means multiply by 1.C41
然后，如果字母是K，就用电阻上标识的值乘上1000；如果字母是M，就用电阻上标识的值乘上10000。如果字母是R，就用电阻上标识的值乘上1.
For example;
例如；
breaches560R means 560 Ω
560R 表示 560 Ω
2K7 means 2.7 kΩ=2 700 Ω
2K7 表示2.7 kΩ=2 700 Ω
39K means 39 kΩ
39K 表示 39 kΩ
1M0 means 1.0 MΩ=1000 kΩ
1M0表示typer 1.0 MΩ=1000 kΩ
1.1.2 Real Resistor Values
实际电阻值
You may have noticed that resistors are not available with every possible value, for example, 22 kΩ and 47 kΩ are readily available, but 25 kΩ and 50 kΩ are not.
你可能已经注意到，不是每一钟常用的阻值都可以很容易被找到，例如，22 KΩ和47 KΩ是很容易能找到的，但25 K和50 KΩ却不容易能找到。
Why so? Imagine that you have decided to make resistors every 10 Q giving 10, 20, 30,4
0，: 5.0 and so. on. That ems, fine，but what happens when you reach 1 000? It would be pointless to make 1 000, 1 010,1 020, 1 030 and so on becau for the .values'. 10 is a very small difference，.too small to be noticeable in most—circuits.. In fact it would be difficult to make resistors sufficiently accurate.庆元旦歌曲
