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To calculate the current through an LED, use the following formula
Current = (Source_voltage - Led_voltage_drop)/Resistance
Now if you didn't use a resistor, the you only have the resistance in the wire, which is very small (eg .001 ohm).
So if you have for instance a 9V battery, and a 2.1 volt drop across the LED, the resultant current would be so high, it would destroy the LED.
We put a resistor in to lower the current to an acceptable range (often 20-30ma)
What else can I help you with?
Components used to protect a LED?
The component used to protect a LED from burning up is called a resistor.
What size of resistor is required to operate the LED from a 9V battery?
In order to determine what size of resistor is required to operate an LED from a 9V battery, first start by knowing the current and voltage required for the LED. That information is available in the LED's specifications. For discussion purposes, lets assume a typical LED at 2.5V and 50mW. The translates to a forward current of 20mA. Build a simple series circuit containing a 9V battery, a resistor of an as yet unknown value, and the LED. By Kirchoff's current law, the current in the LED is the same as the current in the resistor, which is also the same as the current in the battery. This is 20ma. By Kirchoff's voltage law, the voltage across the LED plus the voltage across the resistor equals the voltage across the battery. This is 6.5V. (9 - 2.5) By Ohm's law, resistance is voltage divided by current, so the resistor is 6.5 / 0.02, or 325 Ohms. The nearest standard value to that is 330 Ohms. Cross check the power through the resistor. Power is voltage times current, or 6.5V times 0.02A, or 0.13W. A half watt resistor is more than adequate for this job.
What is the function of the resistor in an led circuit?
current limiter.
How do you connect an LED into a circuit?
A: Add the proper resistor in series with the LED. What resistor? Simple 10volts source minus the LED source divided by the 20ma current that should be flowing gives you the resistor 10-1.8=8.2/.02=900 ohms. The 1.8 can be anything it is up to the LED voltage drop. LONG LEAD IS POSITIVE SHORT IS NEGATIVE SINCE IT IS A DIODE
What is the lifespan of a resistor?
A resistor doesn't deteriorate with age, and has no particular 'life-span', as long as it's used properly. -- A resistor in a box on the shelf, or in a circuit where it stays cool, will last indefinitely. -- A resistor in a circuit where it's forced to dissipate enough power to make it hot may change its resistance value permanently, but will continue to operate. -- A resistor in a circuit where it's forced to dissipate even more than that, to a ridiculous extreme, may melt or explode. When that happens, it's the end of the resistor's life-span. But it wasn't the resistor's fault.
Components used to protect a LED?
The component used to protect a LED from burning up is called a resistor.
Why does a Led have a 470 resistor connected to the LED?
A: That resistor is there to limit the current to the LED it can be any value if the voltage is decreased or increased or no resistor if the voltage across the led is equal to the forward voltage drop.
What size of resistor is required to operate the LED from a 9V battery?
In order to determine what size of resistor is required to operate an LED from a 9V battery, first start by knowing the current and voltage required for the LED. That information is available in the LED's specifications. For discussion purposes, lets assume a typical LED at 2.5V and 50mW. The translates to a forward current of 20mA. Build a simple series circuit containing a 9V battery, a resistor of an as yet unknown value, and the LED. By Kirchoff's current law, the current in the LED is the same as the current in the resistor, which is also the same as the current in the battery. This is 20ma. By Kirchoff's voltage law, the voltage across the LED plus the voltage across the resistor equals the voltage across the battery. This is 6.5V. (9 - 2.5) By Ohm's law, resistance is voltage divided by current, so the resistor is 6.5 / 0.02, or 325 Ohms. The nearest standard value to that is 330 Ohms. Cross check the power through the resistor. Power is voltage times current, or 6.5V times 0.02A, or 0.13W. A half watt resistor is more than adequate for this job.
Why do we put a resistor in series with an LED?
A correctly rated resistor will prevent that the LED is not burnt out if it receives too much power.
Why must an LED always have a resistor connected in series with it?
An LED usually has a resistor connected in series with it because an LED (light emitting diode) is not linear in current to voltage (like a resistor) and has to be operated within specified current and voltage conditions. In most circuits the supply voltage is higher than the forward voltage of the LED so the LED would burn up from too much current without a current limiting resistor in series. The resistor sets the voltage and current to a good operating point (voltage and current) for the LED by dropping some voltage across it. The operating point varies depending on the size, type and manufacturer of an LED so the LED's data is used to select the right resistor size for a given voltage source.
A component used to protect an led in a circuit?
you could use a current limiting diode such as a Zenner, or a current limiting resistor in series with the LED
Why do you need 330 ohm resistor for LED?
Generally 330ohm resistors are used to power a typical 3 volt LED if the source voltage is 5v
How much resistor should use for 20000mcd led?
Has nothing to do with the intensity of the LED, and all to do with the voltage/amperage of thediode, and the voltage of the system it is supposed to be used with.
What is a protective resistor?
The protecting resistor is put in series with the LED so that you have a voltage divider - the supply voltage is split across the LED ( max 0.6v) and the remainder across the protecting resistor. So if your supply is 6volts, 5.4v will be across the resistor,
Which resistor is connect 1.5 volt led to series 220v ac?
Typically, a 100 ohm resistor is used to connect a 1.5 volt led to a series 220v ac adapter. Many LEDs can be connected into a string using the resistors.
What is my Led and what resistor do I need?
Led is a light emitting diodes which can two leads .one lead is larger and the other is smaller. You did't use any resistor because it glows with the small amount of energy! Idiot. I mean't how to I find out what my LED is. I know what a Led is and without a resistor, you prick, It wouldnt last a second.
What is the function of the resistor in an led circuit?
current limiter.
