1. Straight-marking method: The resistance value is marked on the surface of the resistor by the number and unit symbol, and the allowable error is directly expressed by the percentage. If the resistance is not marked, the deviation is ±20%.

2. Text symbol method: The regular resistance is represented by a regular combination of Arabic numerals and text symbols, and the allowable deviation is also represented by a text symbol. The number before the symbol indicates the integer resistance, and the following numbers represent the first decimal resistance and the second decimal resistance. The text symbol text symbol indicating the allowable error: DFGJKM allowable deviation is: ±0.5%±1%±2%±5%±10%±20%

3. Digital method: A three-digit digital representation of the nominal value on the resistor. From left to right, the first and second digits are valid values, and the third digit is the index, which is the number of zeros. The unit is Europe. Deviations are usually indicated by text symbols.

4. Color-code method: Mark the nominal resistance and allowable deviation on the surface of the resistor with different colored bands or points. Most of the foreign resistors use the color standard method.

Black-0, Brown-1, Red-2, Orange-3, Yellow-4, Green-5, Blue-6, Purple-7, Gray-8, White-9, Gold-±5%, Silver-±10 %, colorless - ± 20%

When the resistance is four-ring, the last ring must be gold or silver, the first two digits are significant digits, the third digit is the power square, and the fourth digit is the deviation.

When the resistance is five rings, the distance between the last ring and the front four rings is larger. The first three digits are significant digits, the fourth digit is the power square, and the fifth digit is the deviation.

Identification of the resistance of the chip resistor: On the surface of the usual chip resistors, the numbers are identified or represented by letters. The resistance method is as follows.

1. The first and second digits represent the real number of resistors.

2. If the number starting from the third digit is 0, it means tens of ohms (between 10 and 99 ohms): 100 is the resistance of 10 ohms, and 990 is the resistance of 99 ohms.

3. If the number starting from the third place is 1, it means a few hundred ohms (between 100 and 999 ohms). For example, 101 is 100 ohms, 151 is 150 ohms, and 951 is 950 ohms.

4. If the number starting from the third place is 2, it means several thousand ohms (between 1000 and 9999 ohms). For example, 102 is 1K, 152 is 1.5K, and 992 is 9.9K.

5. If the number starting from the third place is 3, it means tens of K (between 10K and 99K). For example, 103 is 10K, 223 is 22K, and 993 is 99K.

6. If the number starting from the third position is 4, it means several hundred K (between 100K and 999K). For example, 104 is 100K, 204 is 200K, and 854 is 850K.

7. If the number starting from the third position is 5, it means a few M (between 1M and 9.9). For example, 105 is 1M, 155 is 1.5M955 and 9.5M is 9.5M.

8. If the number starting from the third position is 6, it means ten M (between 100K and 999K). For example, 106 is 10M.6 is 56M.

9. For the four digits, the first three digits are real numbers and the fourth digits are multiples. 1001 is 1K, 1002 is 10K, 1005 is 10M