Resistors
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A resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohm's law
                               
                                       R = V/I

The electrical resistance is equal to the voltage drop across the resistor divided by the current through the resistor. Resistors are used as part of electrical networks and electronic circuits
Resistor Color Codings
Four-band identification is the most commonly used color coding scheme on all resistors. It consists of four colored bands that are painted around the body of the resistor. The scheme is simple: The first two numbers are the first two significant digits of the resistance value, the third is a multiplier, and the fourth is the tolerance of the value. Each color corresponds to a certain number, shown in the chart below. The tolerance for a 4-band resistor will be 2%, 5%, or 10%.
Note: red to violet are the colors of the rainbow where red is low energy and violet is higher energy.

As an example, let us take a resistor which (read left to right) displays the colors yellow, violet, yellow, brown. We take the first two bands as the value, giving us 4, 7. Then the third band, another yellow, gives us the multiplier 10 power 4. Our total value is then 47 x 10 power 4 W, totalling 470,000 W or 470 kW. Our brown is then a tolerance of ±1%.

Resistors use specific values, which are determined by their tolerance. These values repeat for every exponent; 6.8, 68, 680, and so forth. This is useful because the digits, and hence the first two or three stripes, will always be similar patterns of colors, which make them easier to recognize.


Mnemonic phrases for remembering codes
There are many mnemonic phrases used to remember the order of the colors.

The easiest way to remember the colors is probably to think of the color spectrum, then add in the numbers. Starting at the lowest values, one goes from black (no color) to brownish (infrared) red (2) green (5) to blue (6) and from there to ultraviolet, almost white, and white light.

In essence, the higher the energy, the higher the number code. In this way, one learns both the basics of visible light in the electromagnetic spectrum and the color codes. They are, but are not limited to, and variations of:

Bye Bye Rose, Off You Go - Birmingham Via Great Western
Bad Boys Ring Our Young Girls But Violet Giggles Willingly
Bad Bacon Rots Our Young Guts But Venison Goes Well. Get Some Now!
B.B. ROY of Great Britain had a Very Good Wife, Good Son
Buffalo Bill Roamed Over Yellow Grass Because Vistas Grand Were God's Sanctuary
Bully Brown Ran Over a Yodeling Goat, Because Violet's Granny Was Gone Snorkeling
Buy Better Resistance Or Your Grid Bias May Go Wrong
Bad Beer Rots Our Young Guts But Vodka Goes Well Good Sir.
Bongo's Buy Randy Ocelot Young Girls Buy Very Groovy Walruses
Black Beetles Running Over Your Garden Bring Very Good Weather
Black Brown Richard Of York Gave Battle In Vain and the Good Women Grieve Sadly
All of the above are mnemonics for the order: Black Brown Red Orange Yellow Green Blue Violet Gray White (Gold Silver None)



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