Electronic Components

Resistors

Background Information

Resistors restrict the flow of electrical current. They do this to prevent damage to electrical components in a circuit. for example L.E.D (light Emitting Diode) require a 1KΩ resistor to prevent it from burning out too quickly and allowing it to last.

They come in a range of values which refer to how much resistance the resistor will create. These values are measured in Ohms (Ω). These resistances will vary from around 1KΩ to a maximum of 1MΩ. 1kΩ is equal to 1000Ω and 1MΩ is equal to 1000000Ω.

The resistance of a resistor is obtained by reading a colour code that is on the resistor this is represented by coloured bands on the component itself. 

this is a 2kΩ Resistor

 The colours represent numbers ranging from 0 - 9 each numeral has its own colour and the position of the colour has a different meaning. The first 2 bands going from left to right are the first 2 numerals of the number and the third band is the multiplier or number of zeros. Referring to picture on left the red is 2 and the black means 0 and the second red is 2 which means two zeros so its value is 2000Ω or 2kΩ. 

The forth band is its tolerance or how much resistance it will have at cold or hot operations. This resistor has a gold band which  means it will have + or - 5% resistance change depending on the resistors temperature.

 Resistor Colour Chart

  Technical Explaination

Resistors are made from two terminals on either side of a carbon rod.

The rod is a form of semiconductor which does not conduct electricity well, and causes resistance, this resistance is created by heat. This causes the current flow to be regulated by it being lost through heat dissipation thus decreasing the current flow in the circuit, which can be used to reduce damage to components, that are not rated to run on the full amount of current flow caused by the voltage source, for example in a12V circuit.

Test Procedure

Testing a Resistor. Resistor tested was a 10KΩ
 the closest rating of the resistor was 9.92KΩ as shown on meter

Testing of resistors is simple all that is required is a multimeter with a resistance setting. Using the probes of the meter on ether side of the resistor a reading can be obtained which is displayed on the meter.     


Problems if Faulty


Resistors are not known to fail often but if they do it is because there has been an excessive voltage surge or wrong value resistor used for application, that causes it to fail. This will cause a break in the circuit stopping current flow.


Reflection


What I learned from working with resistors was how to read the value of a resistor and how the tolerance value effects it, and also how to work out how temperature can effect the resistance it causes. eg.


Brown, Black, Brown, Gold = 100Ω with 5% tolerance (+ or -)
which means with very high or very low temperatures the resistors value or resistance can go up or down


so: 
100Ω-5%= 95Ω when the resistor is at a low temperature.


100Ω+5%= 105Ω when the resistor is at a high temperature.


This can become a large difference depending if the resistor is a high resistance value.