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Of all passive components, the most frequently applied are resistors. Resistors restrict the flow of current in an electrical circuit. The flow of current lowers when there is high level of resistance located in the circuit. The concept of Ohm s Law refers to the connection between current, voltage and resistance. The voltage across a resistor is denoted in volts (V), the current across the resistor in amps (A) and the level of resistance is calculated in Ohms (O). It avoids confusion when the Greek letter for ohms (O) is applied rather than the capital O.
The resistance of a resistor as well as tips on how to write down resistance values.
Although resistors are available with a value a lower than 1 ohm, the majority of the resistors that we use in electronics circuits have greater values of resistance and to prevent getting to write values like 15,000 or 2,200,000 O we use the letter k to imply thousand and M to mean million and we omit the O sign. Additionally, the letter R is sometimes made use of to indicate Ohms. By using k, R or M, the values are depicted clearly when put as a decimal point as it is possible not to discover the decimal points when photocopies are created. For example it is less difficult to create 15k rather of 15,000O and 4M4 instead of 4,400,000O in the conventional form. To write 1.5O you would write this resistance as 1R5 and to create 0.34O, it would read as 0R34. It is also possible to write milli (1/1000th) with the small letter m to point that 3.6 mO means 0.0036 ohms.
Types of resistor marking
The value of resistors is marked with color bands or numbered codes. Through-hole resistors are usually labeled using a range of colored bands. Each color stands for a number. In the case of a 4 band resistor, the first 3 color bands reveals the value of the resistor in ohms and the 4th band reveals the tolerance. Resistors may never be made to a precise value and the tolerance band (the 4th band in this instance) informs us, utilizing a percentage what the margin in resistance is, relative to its coded value. Numerical values with 3 numbers are typically used for SMD resistors coding. This suggests that the first two numbers are the main numbers applied significantly and the 3rd is one factor that is multiplied to the order of 10. For example,in case of a code of 102, the code will equate to 10 x 10^2 = 1 kOhm.
Resistor markings are standardized in international standard by the IEC and the ANSI.
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