Electronics - Diodes and Applications - Discussion
Discussion Forum : Diodes and Applications - General Questions (Q.No. 9)
9.
What is the current through the LED?
Discussion:
35 comments Page 1 of 4.
Rajan said:
9 years ago
@Uma, normally we will calculate resistance after we get the current and voltage. Most semicolons have the different behaviour of I\V curve which actually the resistance curve. In this case, Red Led typically has Vf of min 1.5v. So current calculated as (6-1.5)/330 = 13 mA.
i.e resistance on Diode = 1.5/0.013 = 115 ohm. From here we can anticipate max power loss and heat loss. If too much and the resistance in series can be adjusted.
i.e resistance on Diode = 1.5/0.013 = 115 ohm. From here we can anticipate max power loss and heat loss. If too much and the resistance in series can be adjusted.
Ravi Shankar Kumar said:
1 decade ago
If you don't remember the forward voltage of the LED then use simple common sense that if that(LED) is not there then current in the circuit will be 18mA so if it is present then current must be lesser than 18mA because of resistance offered by LED ,only option is 13mA which is lesser than 18mA :P
(1)
Srivalli said:
1 decade ago
Typically, a LED forward voltage is about 1.8–3.3 volts; it varies by the color of the LED. A red LED typically drops 1.8 volts, but voltage drop normally rises as the light frequency increases, so a blue LED may drop around 3.3 volts.
Akash tanna said:
1 decade ago
There is not any single device which have't any resistance and it is having some resistance then due to the currrent passing loss will be generated on the bases of I2R losses equation.
Amit said:
1 decade ago
To akansha LED is always operated in forwar bais. Not reverse.
Anoth note to all friends.
If question said IDEAL DIOD then voltage drop is 0.
Anoth note to all friends.
If question said IDEAL DIOD then voltage drop is 0.
Akanksha said:
1 decade ago
Can anybody tell me what will be the result if LED is inverted. Will the led drop voltage add to 6V. ? it was asked me in my practical exam.
Surendra said:
1 decade ago
LEDcolour Forward voltage (volt).
1. Infrared 1.3 to 1.5.
2. Red 1.5 to 1.8.
3. Yellow 2 to 2.2.
4. Green 2.2 to 2.4.
5. Blue 3 to 5.
1. Infrared 1.3 to 1.5.
2. Red 1.5 to 1.8.
3. Yellow 2 to 2.2.
4. Green 2.2 to 2.4.
5. Blue 3 to 5.
(1)
Uma said:
1 decade ago
Someone said that LED has resistance so there is voltage drop ! I want to know, what is resistance of LED ? And how can we measure that?
Anbu said:
1 decade ago
I think the Led drop volatage will vary according to the various leds like red, blue, so normally we can judge 1.5v na?
Devidas K said:
1 decade ago
No. Led having its own resistance that is self resistance so some voltage must be drop across it.
Answer is correct.
Answer is correct.
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