The Importance of Voltage in Electrical Components

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Discussion Overview

The discussion revolves around the significance of voltage in electrical components, particularly focusing on LEDs. Participants explore the relationship between voltage and current, the implications of voltage ratings, and how these factors influence the operation and longevity of LEDs.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions the importance of voltage compared to current, specifically regarding the voltage rating of an LED.
  • Another participant explains that the 2.1V rating refers to the forward voltage at which the LED operates optimally at 20mA, suggesting the use of a constant current power circuit.
  • A different participant emphasizes that exceeding the maximum current rating of 20mA can significantly reduce the lifespan of the LED.
  • One participant discusses the practical implications of voltage, noting its importance in determining how many LEDs can be connected in series and the feasibility of powering them from various voltage sources.
  • Another participant provides an analogy comparing voltage to water pressure and current to water flow, highlighting that without voltage, current cannot flow.

Areas of Agreement / Disagreement

Participants express varying views on the relationship between voltage and current, with some emphasizing the critical role of voltage in LED operation while others focus on current. The discussion does not reach a consensus on the relative importance of these factors.

Contextual Notes

Some assumptions about the operating conditions of LEDs and the definitions of voltage and current are not fully explored. The discussion also does not resolve the implications of different voltage sources on LED performance.

tkahn6
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I suspect this is a very stupid question but:

Why is voltage across a component (say, an LED) important? Isn't current the only important factor?

If it says on the package 2.1V, 20mA. What does this mean?

Does it not matter if I connect it to a voltage of 5V over 250Ω or 3V over 150Ω?

Thanks guys!
 
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I believe the 2.1v would be the forward voltage, the voltage the LED will run at when it's limited at 20mA, like if you used a constant current power circuit. Check this site http://led.linear1.org/1led.wiz for a nice LED calculator.
 
20ma is the max current rating of the diode. If you do not limit diode current to less then 20ma the life of the diode will be seriously compromised.
 
The voltage across a LED when it is operating is very important.

It tells you how many LEDs you can put in series across a 12 volt supply to make Christmas lights, for example.

It tells you if you could power the LED from a single 1.2 volt NiCd battery.

You have to put limiting resistors into limit the current, of course, and if you have plenty of voltage to spare, you only have to worry about the current. But it is those times when you are trying to run something off a low voltage when it really matters how much voltage is across each LED.

Also, different coloured LEDs have different voltages across them, so a colour that will not work could be replaced by one that will.
 
First the voltage definition is the potential difference between two ends. the current is the flow of the electrons. let me tell you some simple example think about the over head tank - the voltage is the pressure difference between tank and the tap but current can be compared with flow of the water. without potential difference (voltage) the flow of electron (current) can not exist.
 

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