Identification of resistance and capacitance
Time:2022-07-06
Views:2038
一、 Color ring representation of resistance value
1. Correspondence between color and number:
Note: when gold and silver appear in the fourth ring, they represent error, gold represents 5%, and silver represents 10%; When the third ring appears, gold represents 0.1 and silver represents 0.01. Please see the following example.
2. "Four color ring" reading rule:
First, the second ring represents two significant digits, and the third ring represents the number of "0" added after the number. For example:
Example 1:
Resistance value: add "3 zeros" after 27, that is, 27000 Ω, with an error of 5%
Example 2: if the third ring is gold
Resistance value: 27 decimal point is moved forward by 1 place, that is, 2.7 ohms, with an error of 5%
Example 3:
Resistance: add a 0 after 22, that is, 220 ohms, with an error of 5%
Example 4:
Example 4 shows a resistance of 22 ohms. The third ring "black" means "0 zeros", which means that 0 is not added after the number.
In fact, the third ring is expressed in mathematical form as the power of 10 to the power of N. the previous cases can be written respectively:
twenty-seven × 103＝27000
twenty-two × 101＝220
twenty-two × 10°＝22
1000 Ω =1 kilo Ω, 1000 kilo Ω =1 megaohm. The symbol of ohm is Ω; Kilo ohm: Κ Ω; Megohm: m Ω.
3. "Five color ring" reading rule:
The first, second and third rings represent three digits, the fourth ring represents the number of "0" after the number, and the fifth ring represents accuracy. Now the market is gradually dominated by five color rings, and the actual use of the expression method of the accuracy of the fifth ring is different from the relevant provisions in the past. Generally, Brown is used to represent the error of 1%. Examples are as follows:
Example 5:
The resistance value of this resistance: 200000 ohms = 200K, error 1%
Green = 5, brown = 1, black = 0, silver = 0.01, then
Resistance value = 510 × 0.01＝5.1Ω
II. Expression method of capacitor capacity
The basic unit of capacitor capacity is "farad" (f), and 1/1000000 (one millionth) of 1 farad is 1 micro method（ μ F) , 1/1000000 of 1 micro method is 1pf (1 micro method, or 1 skin method). The relationship between them is the carry relationship of millions (or the 6th power of 10).
Our commonly used capacitors are:
1. Dielectric capacitance: mostly at 1 μ Above F, directly expressed in numbers. For example: 4.7 μ F 、 100 μ F 、 220 μ F, etc. The two poles of this capacitor are positive and negative, and the long leg is the positive pole.
2. Ceramic chip capacitance: mostly at 1 μ Below F, directly expressed in numbers. For example, 10, 22, 0.047, 0.1, etc. pay attention to the unit here. If expressed as an integer, the unit defaults to PF; Where decimal is used, the unit is defaulted μ F 。 As in the above example, they are 10p, 22P and 0.047 respectively μ F 、 220 μ F, etc.
Now another expression similar to the color ring resistance is popular internationally (the unit is pf by default):
For example, "473", i.e. 47000 pf=0.047 μ F
"103" means 10000 pf=0.01 μ F, etc,
The first and second digits of "XXX" are significant digits, and the third digit represents the number of 0 added later. This representation is already quite common.
The first and second digits of "XXX" are significant digits, and the third digit represents the number of 0 added later. This representation is already quite common.
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