Hi to all of you! We learned the fundamentals of microcontrollers in the last post. Today, let's get introduced to LED, one of the most crucial electronic components, and how to use them.
OHM'S LAW
Knowing Ohm's Law is essential before beginning any electronics course since it forms the foundation of our comprehension of the relationship between voltage, current, and resistance.
Picture taken from build-electronic-circuit.com
Take a look at the image above. Think of Voltage as the pushing force which results in the movement(current). The faster you push; the speeder will be the movement. That is,
Current ∝ Voltage
The opposition provided to the current flow is known as the resistance, and it is measured in ohms. Even with increased voltage, current will be lower when resistance is higher.
Current ∝ 1/Resistance
Combining the above two relation, we get the Ohm's Law:
Current = Voltage / Resistance
LIGHT EMITTING DIODE
To put it simply, an LED is an electrical device that emits light when current flows through it. It is easy to use and available in a variety of colors. It will illuminate if you simply apply some voltage (like a 9V battery) between the terminals.
Caution: Don't connect 9V battery directly to an LED. Always connect it in series with a 330ohm(or some nearby value) resistor, as the resistance of the led is very small (Don't forget Ohm's Law!!) .
As you can see in the above image, the LED has two terminals : Anode(Positive side) and Cathode(Negative side). When voltage is applied between these two terminals, current starts to flow, emitting light. In other words,
Light Intensity ∝ Current Flowing through the diode
Note: Typical Max current rating of a led is 20mA (Because of its lesser power consumption, it is being preferred nowadays in many applications)
Let's try to create a simple circuit to make the led to work.
Time for some math! The voltage applied to the led and resistor combination is 9V. Generally, Leds drop around 1 to 2V (depends on led color). So the remaining voltage across the resistor is 9-1 = 8V. And the value of resistance is 470 ohm. From Ohm's low, we can find
Current = Voltage / Resistance = 8 / 470 = 17 mA (Within 20mA, the safe limit)
In this post, we got to know about how Leds work and how to make a useful circuit out of it.
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