Why resistor led

Oyvind as per my query is this what prevents the diode from burning up as the cathode, electron side is connected directly to the battery negative side without a resistor. Now you confirmed that a resistor anywhere in that circuit will slowdown the electron speed through the LED. One resistor for the whole circuit? One resistor for each LED? No resistors at all because the voltages match?

Can you help me with this? Most likely, it would work — the LEDs would light up. It could be high, it could be low. Your email address will not be published. If the LED gets too much current flowing through it, it will burn out and die. So it always needs a resistor to protect it. But, in which order? Diodes including LEDs are non-linear. That is, their resistance changes with the applied voltage. Below the "breakdown" voltage "operating" voltage for an LED there is a lot of resistance and almost no current flows.

Above the breakdown voltage, the resistance becomes almost zero and you'll get as much current as the Arduino or other circuit can provide. By limiting the current with a resistor or other current-limiting circuit and operating the LED at the correct current, the correct voltage "falls into place" and the remaining voltage is dropped across the resistor. It's true that you cannot get more than 30mA with a Ohm resistor connected in series.

But you'll actually get less. With about 2V dropped across the LED, you'll have about 3V dropped across the resistor and about 18mA through the resistor. See " Procedure: " at end for a step by step application of this. In reality currents will be somewhat higher as typical Vfs I used are at 20 mA typically. At lower currents Vf is lower see LED data sheets and so R has more voltage drop so there is more current so Python Javascript Linux Cheat sheet Contact.

Why we use ohm resistor to connect a LED? The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why do we need resistors in led Ask Question. Asked 9 years, 7 months ago. Active 3 years, 10 months ago. Viewed 76k times. WantIt WantIt 2, 9 9 gold badges 35 35 silver badges 54 54 bronze badges.

Add a comment. Active Oldest Votes. It is an OK assumption for this example but a dangerous one in general. Which assumption do you mean? An oscillator with eg series LC would probably be a useful example. You understand that such things can happen even if we don't usually put things in those terms but a raw beginner will have no concept of AC operation etc. Show 2 more comments. VariableLost VariableLost 41 1 1 bronze badge. While you may get a way with this - if anything changes in the curcuit, the LED is on it's own.

Why infinite in the first place? It is not relevant to this question but extremely important to know that your statement that "we know that series ciircuit, the current is constant at every point. Russell, could you give an example for a series circuit where current is NOT equal through all elements? It can also mean "independent of load changes", for example in a "constant-current source". The specific phrase "constant at every point" means that the parameter in question current IS a function of location and nothing else.

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