Resistor Code

The electronic color code is used to indicate the values or ratings of electronic components, very commonly for resistors, but also for capacitors, inductors, and others. A separate code, the 25-pair color code, is used to identify wires in some telecommunications cables.

Resistor Color Code Chart

Band Color Options Band #1 Possible Band #2 Possible Band #3 Possible Multiplier Value For Band 3 Band #4 Value Tolerance Black 0 1 1 Brown 1 1 1 10 ±1% Red 2 2 2 100 ±2% Orange 3 3 3 1,000 Yellow 4 4 4 10,000 (±5%) Green 5 5 5 100,000 ±0.5% Blue 6 6 6 1,000,000 ±0.25% Violet 7 7 10,000,000 ±0.1% Gray 8 8 100,000,000 ±0.05% (±10%) White 9 9 1,000,000,000 None 20% Silver 10% Gold 5%

Resistor Color Code Information

The resistor color code is a long standing standard in both the electronics and electrical industries, indicating the value of resistance of a resistor. Resistance is measured in ohms and there is a foundation for it called Ohm's Law. Each color band represents a number and the order of the color band will represent a number value. The first 2 color bands indicate a number. The 3rd color band indicates the multiplier or in other words the number of zeros. The fourth band indicates the tolerance of the resistor +/- 20%, 10% or 5%. In most cases, there are 4 color bands. However, certain precision resistors have 5 bands or have the values written on them, refining the tolerance value even more. There is no standard (TANS) however, for the 5th band. From one manufacturing company to another, the 5th band may indicate 2%, 1%, 1/2% or even closer, according to their own standards. Color bands are usually found on resistors that have a wattage value of 1/8 to 2 watts; though it is rare, there are some 5 watt resistors that are banded. There are also some capacitor that are color-coded. 

Resistor color-coding

To distinguish left from right there is a gap between the C and D bands.

• band A is first significant figure of component value (left side)
• band B is the second significant figure (Some precision resistors have a third significant figure, and thus five bands.)
• band C is the decimal multiplier
• band D if present, indicates tolerance of value in percent (no band means 20%)

REFERENCE:
en.wikipedia.org/wiki/Electronic_color_code
http://www.csgnetwork.com/resistcolcalc.html

Ohm's Law

THE OHM'S LAW


PARALLEL CIRCUIT - A parallel circuit has more than one resistor (anything that uses electricity to do work) and gets its name from having multiple (parallel) paths to move along . Charges can move through any of several paths. If one of the items in the circuit is broken then no charge will move through that path, but other paths will continue to have charges flow through them. Parallel circuits are found in most household electrical wiring.


COMPUTING PARALLEL CIRCUIT
The following rules apply to a parallel circuit:

1. The potential drops of each branch equals the potential rise of the source.
2. The total current is equal to the sum of the currents in the branches.
3. The inverse of the total resistance of the circuit (also called effective resistance) is equal to the sum of the inverses of the individual resistances. One important thing to notice from this last equation is that the more branches you add to a parallel circuit (the more things you plug in) the lower the total resistance becomes. Remember that as the total resistance decreases, the total current increases. So, the more things you plug in, the more current has to flow through the wiring in the wall. That's why plugging too many things in to one electrical outlet can create a real fire hazard.

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SERIES CIRCUIT - A series circuit has more than one resistor (anything that uses electricity to do work) and gets its name from only having one path for the charges to move along. Charges must move in "series" first going to one resistor then the next. If one of the items in the circuit is broken then no charge will move through the circuit because there is only one path. There is no alternative route. Old style electric holiday lights were often wired in series. If one bulb burned out, the whole string of lights went off. 


COMPUTATION FOR SERIES CIRCUIT
The following rules apply to a series circuit:

1. The sum of the potential drops equals the potential rise of the source.
2. The current is the same everywhere in the series circuit.
3. The total resistance of the circuit (also called effective resistance) is equal to the sum of the individual resistances.

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REFERENCES:
 http://www.regentsprep.org/Regents/physics/phys03/bparcir/
http://www.regentsprep.org/Regents/physics/phys03/bsercir/default.htm