Resistor or commonly referred to (Dutch) werstand, prisoner or barrier, is an electronic component that provides resistance against the displacement of electrons (negative charge). Resistors abbreviated with the letter "R" (capital R). The unit is ohm resistors, which find is George Ohm (1787-1854), a German physicist. Detainees in this section called conductance. Unit conductance was written with the inverse of Ohm that is mho.
Ability to inhibit resistor is also called resistance or electrical resistance. The magnitude is expressed in units of Ohms. A resistor is said to have a 1 ohm resistance when the resistor bridge voltage difference of 1 volt and electric current arising due to stress is amounting to 1 ampere, or equal to as much as 6.241506 × 1018 electrons per second flowing in the opposite facing direction of flow.
The relationship between resistance, voltage, and current, can be summarized through the following law, which is known as Ohm's law where V is the potential difference between the two ends of the object block, I is a large current through the body block, and R is the resistance of the resistor body .
Function is to resist the resistor voltage electrical current. The greater the resistance value of resistor then the voltage and current that flows will be smaller. Vice versa.
In the resistor we can determine its value based on existing codes of color bands on the resistor. Resistors with 4 ring color Calculate the resistor value by looking at the color code.
resistors made of several materials that can deliver electrical current:
Carbon Composition
Carbon composition resistors consist of solid cylindrical resistive element with embedded lead wires or metal cap end of the lead wires attached. Resistor body is protected with paint or plastic. Early 20th century carbon composition resistors have uninsulated body; lead wire wrapped around the tip of the stem and the resistance element is soldered. Resistors finished painted for color coding of the value.
The resistive element is made from a mixture of finely ground (powdered) carbon and insulation material (usually ceramic). A resin mixture holds together. Resistance is determined by the ratio of filling materials (ceramic powder) to the carbon. Higher concentrations of carbon, a weak conductor, resulting in a lower resistance. Carbon composition resistors are commonly used in the 1960s and before, but not so popular for general use now as other types have better specifications, such as tolerance, voltage dependence, and stress (carbon composition resistors will change value when the stress with over- voltage).
In addition, if the internal moisture content (from exposure to some period of time to humid environment) is significant, solder heat will create a non-reversible change in resistance value. This resistor, but if have never experienced transient overvoltage is not too hot that is very reliable. They are still available, but relatively quite expensive. Values range from fractions of an ohm to 22 megohms.
Carbon film
A carbon film was deposited on insulating substrate, and a helical cut to create a long, narrow resistive path. Various shapes, plus the resistance of carbon, (range 90-400 nΩm) can provide a variety of resistance. [1] of Carbon film resistors feature a wide power rating 0.125 W to 5 W at 70 ° C. The available resistance range from 1 ohm to 10 megohm. Carbon film resistor can operate between temperatures -55 ° C to 155 ° C. It has a maximum working voltage of 200-600 volt range.
Metal film
Common types of axial resistor today is referred to as a metal film resistors. Leadless metal electrode face (MELF) resistors often use the same technology, but it is a cylindrically shaped resistor designed for surface increases. Note that other types of resistors (eg, the composition of carbon) is also available in the MELF package. Metal film resistors are usually coated with nickel chromium (NiCr), but may be coated with one of the cermet materials listed above for thin-film resistors. Unlike thin film resistors, the material can be applied using different techniques than sputtering (although it is one such technique). Also, unlike thin-film resistors, the resistance value is determined by cutting a helix through the layers rather than by the etching. (It is similar to the way carbon resistors created.) The result is a reasonable tolerance (0.5, 1, or 2%) and temperature coefficient (typically) 25 or 50 ppm / K.
Foil resistors
The main barrier foil resistor element of a special alloy foil a few micrometers thick. Since the introduction in the 1960s, foil resistors have the best precision and stability of each resistor is available. One of the important parameters that affect the stability of the temperature coefficient of resistance (TCR). The TCR of foil resistors is very low, and has been further enhanced over the years. A range of ultra-precision foil resistors offer a TCR of 0.14 ppm / ° C, tolerance ± 0005%, long-term stability (1 year) 25 ppm, (3 year) 50 ppm (more increased 5-fold by the hermetic sealing) , stability under load (2000 hours) 0.03%, a thermal EMF 0.1 μV / ° C, -42 dB of noise, voltage coefficient of 0.1 ppm / V, 0.08 μH inductance, capacitance of 0.5 pF.