Showing posts with label Resistance. Show all posts
A resistor is one of the most fundamental components in electronics. Its purpose is to impede a flow of current and impose a voltage reduction. It consists of two wires or conductors attached at opposite ends or sides of a relatively poor electrical conductor, the resistance of which is measured in ohms, universally represented by the Greek omega symbol, Ω.
To understand what a resistance do in electrical circuit, let us have a look at given figure
As from the figure it is easily understood that as soon as kid put his feet on the pipe, it results into reduced flow of water. The same work is done in electrical circuit with the help of resistance.
Resistance in a electrical circuit reduces magnitude of current flow. And cause a voltage drop across, so we can use resistance in our circuit when ever it is needed to reduce current through a specific circuit or we want to divide current in the circuit.
Schematic symbols that represent a resistor are shown in Figure.
Uses of resistors in electronics :
A resistor is commonly used for purposes such as limiting the charging rate of a capacitor; providing appropriate control voltage to semiconductors such as bipolar transistors; protecting LEDs or other semiconductors from excessive current; adjusting or limiting the frequency response in an audio circuit (in conjunction with other components); pulling up or pulling down the voltage at the input pin of a digital logic chip; or controlling a voltage at a point in a circuit.
Colour coding:
To express the value of the component, each of the first two bands representing a digit from 0 through 9, while the third band indicates the decimal multiplier (the number of zeroes, from 0 to 9, which should be appended to the digits). A fourth band of silver or gold indicates 10% or 5% tolerance respectively. No fourth band would indicate 20% tolerance, although this has become very rare.
Two sample resistors are shown in figure above. The upper one has a value of 1K, indicated by the brown and black bands on the left (representing numeral 1 followed by a numeral 0) and the third red band (indicating two additional zeroes). The gold band at right indicates a precision of 5%. The lower one has a value of 1.05K, indicated by the brown, black, and green bands on the left (representing numeral 1 followed by numeral 0 followed by a numeral 5) and the fourth band brown (indicating one additional zero). The brown band at right indicates a precision of 1%.
