RESISTOR

What is a Resistor?

A resistor is simply a conductor that opposes the flow of electric current to one (1 A) amperes when a voltage of (1V) one volt pass through it. Also, a resistor is an active element which can either be a carbon type or choke or wired-wound type. This component that renders a resistance to the flow of electric current plays a major role in the electronics industry today. Below is a symbol of a resistor and structural view as likely available in the markets.

The amount of resistance introduced by the resistor is what determines the amount of current flow through the conductor or circuit. This amount or level of resistance is measured by a rate of unit known as Ohms. And the standardized abbreviation in representing a resistor is R. Ohms law states that. The resistance of a resistor is dependent on the composition of material it’s made up of also known as its resistivity, also its dimension and object temperature involved. The Resistivity of a resistor is defined in terms of the ohms resistance per cubic centimeter of that substance at a temperature of 20 degree Celsius.

Applications of Resistor

A Resistor can be applied in various ways in both electronics industry and circular world at large.

-A resistor can be use as heating element in households.

In areas of cold temperature such as homes in parts of the world as Russia, Germany, and certain parts of United states, heating elements are use to keep the room temperature at a safe level needed for the body. Below shows a heating element design for homes.

- In Incandescent Lamps:

resistors are designed to produce illumination in glass tubes to provide light for visual and even around the premises for security surveillance. Below is a basic incandescent lamp

- Electronics circuitry:

where adjustment is needed to regulate the inflow of current. Certain resistors made adjustable known as rheostat or variable resistors, when adjusted they offer certain level of resistance to current flow in increasing and decreasing pattern respectively depending on the intention of the circuit designer. Variable resistor are also use in volume control in audio systems where the level of audio signal is to be regulated in amplifiers both in home-theaters, radio systems, transmitters and so on. Below shows the symbol of a variable resistor and its structural diagram.

-In Dimmer.

Certain room lighting system requires dim light (low illumination or intensity of light in the room). Variable resistors are applied to regulate or adjust the rate of flow of current in the circuit of the Dimmer thereby providing a Dull Like illumination suitable for sleeping mood at night.

Resistor Color Code

Resistors are made such as to have values of resistance in order for anyone to be able to identify and apply it independently. This is made possible by coloring. Commonly used resistors are those with four (4) colors. The last color hereby denotes its tolerance.

The color codes are arranged much that the colors seem closer to one part of the terminal than the others. Below shows a resistor and its color code written on it. The side of color closer to the terminal I indicate the start point or point to begin counting from for identification. The last color is known as the tolerance. As we humans have limit to which we can admit or accommodate things in life, so also a resistor has a limit known as tolerance to which it can withstand certain amount of current been passed through it.

The color band of the resistors and their equivalent digits are listed below:

B- Black- 0, B- Brown- 1, R- Red- 2, O- Orange- 3, Y- Yellow- 4, G- Green- 5, B- Blue- 6, V- Violet- 7, G- Gray- 8, W- White- 9,

Tolerance: Gold=±5%, Silver= ±10%. Note also that the first and second colors are the digits of the resistor value. The third color is the multiplier x10, and the fourth digit is the tolerance.

Below shows the diagram and color band on the resistor and how to calculate a certain resistor:

For instance, a resistor having colors of Red, Green, Yellow and Gold. The resistance values will be calculated as:
Red=2, Green=5, Yellow=10¬4¬¬ ¬Gold= ±5% 2 and 5 multiply by10¬4¬¬ ¬¬ ±5% 25*10¬4¬¬ ohms ±5% 250000 ohms ±5% = 250KΩ, ±5% = 12500Ω
Therefore, the total resistance becomes 250kΩ + 12500Ω = 262500Ω and 250KΩ-12500Ω= 237500Ω This means that, the resistor can tolerate between 262500Ω and 237500Ω.

These are just the few types of resistor whose resistance can be calculated using color code. There are some that their values are written directly on their body. Examples of those are Choke resistors. The picture below shows such resistor.

Other types such as potentiometer used as volume controls, their resistance value are written on their body in the form of multiplier such as 503 = 50kΩ, 104 = 100KΩ and so on.

Thanks for taking time to read through, I wish we make it a date next time as I keep you updated on basic electronics components, uses and circuits idea and applications generally.

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