What is a Resistor | Types of Resistor, Function, Color Code, Symbol

Now Let's Learn about Resistor – Different Types of Resistor, their Color Code, Function, Examples, Symbol, and Application Explained in Detail.

What is a Resistor?

Many of you might be asking what is Resistor, now get your jotter and put it down, Resistor is known to be an electrical device that resists the flow of electrical current. Note that it is a passive device which is use to control, or impede the flow of, electric current in an electric circuit by providing resistance, thereby developing a drop in voltage across the device.

Meanwhile we need ways to control the flow of current which come's from a voltage source, like a battery, so we do not end up melting wires and blow up batteries.

When we talk about current, the charge flow, when it comes to the of terms of water flow, know that a good electrical conductor is like big water pipe. We all know that water mains and fire hoses have their own uses, which you do not want to take a drink from any of them. Rather, we prefer to use a small pipes, valves, and other devices to control water flow to practical levels. however know that Resistors do the same when it comes to current; there work is to resist the flow of charge; they are poor conductors.

How is a Resistor Made?

You might be asking your self this, how do resistors made, though there are many ways to make a resistor. Meanwhile note that Some of this resistors are just a coil of wire made of material which is a poor conductor. Meanwhile one of the most inexpensive and common type is being created from powdered carbon and a glue-like binder. Though Such carbon composition resistors normally have a brown cylindrical body with a wire attached on each end, with a colored bands which indicate the value of the resistor.

Resistance Materials

Note that all this Resistors are creati from a number of different materials. I will only concentrate on the some of most common varieties, and the attributes which i have described for each are typical, although there will be variations from different makers, and specialized types which doesn't follow this (very) basic characteristics. Moreover all resistors are comparatively cheap.

1. Metal Film

Low to medium power. Very good tolerance and stability. Quiet.

2. Carbon Film

Low power. Reasonable tolerance and stability. Reasonably quiet.

3. Carbon Composition

Low to medium power. Comparatively poor tolerance and stability. Noisier than most others.

4. Wirewound

High to very high power. It accept very good tolerance, good stability. Quiet. May have inductance.

Resistors usually make some kind of noise. Meanwhile anything which is above 0K (zero Kelvin, absolute zero, or even -273 degrees Celsius) must makes noise, and the resistors are no exception. Meanwhile Noise is proportional to the temperature and voltage. Know that the low noise circuits will always make use of low resistor values and low voltage wherever possible. However, Resistors may also have inductance, and Wire-wound types are the worst for this. Bear in mind that there are non-inductive Wire-wound resistors, but are not readily available, and they are usually not cheap.

What is a Potentiometer?

This Resistor known as potentiometer is a variable resistor, because when the knob of this potentiometer is turned, a slider moves along the resistance element. Moreover this Potentiometers generally have three terminals,the first is a common slider terminal, and the second is one that exhibits increasing resistance and the third is the one that has a decreasing resistance relative to it's slider as the shaft is turned in one particular direction.

Meanwhile the resistance between the two stationary contacts is, of course, fixed, and it is the value that specified for the potentiometer. In the other hand the photo resistor or photocell as you prefer to call it is composed of a light sensitive material. But know that whenever this photocell is exposed to more light, It's resistance decreases. Moreover this kind of resistor makes an excellent light sensor.

How is Resistance Measured

Note that the actual value of resistor is measured in ohms and they're represented by the Greek letter capital omega (Ω).

Meanwhile it's resistance value is being specified in ohms, the standard symbol is “R” or Ω. Resistor values are usually stated as “k” (kilo, or times 1,000) or “M“, (meg, or times 1,000,000) for convenience.

There are a some conventions that followed, and this may cause problems for the beginner. To explain this – the resistor has a value of 2,200 Ohms. This may be shown as any of these:

2,200 Ohms

2,200 Ω

2,200R

2.2k

2.2k Ω

2k2

Generally the uses of this symbol for Ohms (Omega, Ω) is optional, and it is commonly left off, since it is irksome to add from keyboards.

Meanwhile this letter “R” and “2k2” conventions Note that they are European, and they are not commonly seen in US and other backward countries Other variants are 0R1, for example, which simply means 0.1 Ohm.

Schematic Symbol of Resistor

Generally the schematic symbols for resistors are those shown below. Meanwhile i make use of Euro version of this symbol exclusively.

Formula to Calculate Resistance

Moreover the basic formula for resistance is Ohm’s law, which normally states that:

R=V/I: know that V is voltage, while I is current, and then R is resistance.

Meanwhile the other formula you may need with resistance is Power (P):

P=V2/R

P=I2*R

Meanwhile the easiest means to transpose any formula is what we call the “Transposition Triangle” – which may (and will) be applied to other formulae. Further more this resistance and power forms will be shown below, all you need is just cover the value you want, and the correct formula is shown. Just In case you ever wondered why they had to do algebra at school, you now know, that it is primarily way for the manipulation of a formula,which they just don’t teach the simple ways.

Meanwhile know that a blank between two values simply means they're multiplied, and the line means peak. 

 What's Tolerance of a Resistor? 

 I know you'll be asking yourself what's forbearance of a resistor, Now the forbearance of resistors is substantially 1, 2, 5 and 10. During the old days, 20 was also common, but these are now rare currently. also indeed the 10 resistors are veritably hard to get except in extremely high or low values(> 1M or< 1R), where they may be the only options available at a sensible price. 

 However the 100R resistor with 5 forbearance may be anywhere between 95 and 105 ohms – though in utmost circuits this is insignificant, but there will be occasions where veritably close forbearance is demanded(e.g.0.1 or better). Meanwhile this is fairly rare for audio, but know that there are many cases where you may witness similar close forbearance factors. 

 Power Standing of Resistor 

 This Resistors are available with power conditions of 1/ 8th W( or lower for face mount bias or SMD), up to hundreds of watts. Although the most common are 1/ 4W(0.25 W), 1W, 5W, 1/ 2W(0.5 W), and 10W. There are just many systems bear advanced powers, and it's frequently much cheaper to use multiple 10W resistors than a single( say) 50W unit. typically they will be veritably much easier to gain. 

 Just like all factors, they're preferable to keep temperatures as low as possible, so no resistor should be operated at its full power standing for any extended time. That why i always recommend a outside of0.5 of the power standing whenever possible. 

 Meanwhile Know that line crack resistors has the capability to tolerate severe overloads for a short period, but I generally prefer to keep the absolute outside to kindly

 lower than 250 – indeed for a veritably brief ages, also since they may come open circuit from the stress, rather than temperature( though this does be, which i've endured it during tests and repairs).