Sunday, 18 June 2017

Three methods of finding Anode and Cathode of the LED (Light Emitting Diode)


Q) WHAT IS LED?????????
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated.[5]When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the colour of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor. LED's are typically small (less than 1 mm^2 ) and integrated optical components may be used to shape the radiation pattern.

HOW DOES LED LOOKS LIKE?

Different Types of LED's
Symbol of LED


HOW TO FIND POSITIVE (ANODE) AND NEGATIVE (CATHODE) TERMINAL...........


It's quiet easy............
There are three methods:-

FIRST METHOD


By looking at there legs we can figure out the anode and cathode.
The Leg are of different size,  i.e., The shorter leg is the NEGATIVE or CATHODE of the LED and the longer one is the POSITIVE or ANODE.
So simple.
A Normal LED
This LED has legs of different length but there is a possibility that you get the LED with both legs of same length.
LED with both legs of same length

Now what to do, here comes the 

SECOND METHOD


By looking inside the LED.
You can look inside the LED and find the ANVIL and POST.
 
In this figure you can clearly see two structure of different width. The one with the greater width is the ANVIL and other is POST

So now clearly the Anvil that has the greater width and is NEGATIVE or CATHODE where as the Post has the smaller width and is POSITIVE or ANODE of LED.


There is one more possibility that your not able to see though the LED and cannot figure out the ANVIL and the POST or you can say CATHODE and ANODE, So what now......


THIRD METHOD


So in this method you can touch the sides of the LED and search for a flat spot.
The leg near the flat spot or edge is CATHODE or NEGATIVE.
So you can clearly differentiate the POSITIVE and NEGATIVE leg of the LED.

Flat spot in LED

This was the last method for finding ANODE and CATHODE.

If you are unable to find these three things then the last option is to check it by connecting it to the battery.

WARNING :- Always remember to connect a resistor of suitable value to limit the excessive current else you might damage or burn the LED.

YOU CAN ALSO SEE VIDEO ON THE SAME EXPLAINING IT :-

                                 


This was all about finding the LED Anode and Cathode.


Note:- Some images are taken from the net we thank all the source. This is meant for educational purpose only.

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