current limiting resistance placement matters or not which circuit is correct....??

[aliraza786]

current limiting resistance placement matters or not which circuit is correct....??

Image replaced with gif format [alexan_e]

 

[tushki7]

Hello.. It will be same in both the cases .. Here is an example : :twisted:

 

[Tahmid]

It's the same thing. The two components (resistor and LED) are in series. So, the same current flows through both the components, so, it does not matter where the resistor is placed. Before or after the LED, current will pass through it either way and the resistor will do its job in limiting the current.

Hope this helps.
Tahmid.

 

[aliraza786]

Thnks tahmid and tushki for your urgent replies..i know you All are right but i have a question in technical paper the which circuit is more prefreable and why...i know your all logic 100% corect but i coudnt understand the question how can we prefer one circuit another when both doing the same thing..but one thing we have to consider we always conect resistance first then Led in all books in all website we found the same thing but no one use led first then resistance...

 

[Tahmid]

Usually, resistor is connected first, then the LED. It's just a common practice. However, it makes no difference which way you wire it. A simple analogy: If you had to pick up a pencil, you could do it with your left hand or right hand. Either way, you'll be able to pick it up. However, most people tend to use their right hand and it's common practice.

 

[pbdavis73]

Usually, resistor is connected first, then the LED. It's just a common practice. However, it makes no difference which way you wire it. A simple analogy: If you had to pick up a pencil, you could do it with your left hand or right hand. Either way, you'll be able to pick it up. However, most people tend to use their right hand and it's common practice.

I guess it depends on whether you are right hander or left hander rather....not because of common practice....bad analogy...

 

[kripacharya]

Hello.. It will be same in both the cases .. Here is an example : :twisted:
View attachment 59982

its interesting to note that the current is not the same for all in your example. how did you do this...??

- - - Updated - - -

I guess it depends on whether you are right hander or left hander rather....not because of common practice....bad analogy...

i think what he meant was ... whatever is convenient for you.

- - - Updated - - -

Thnks tahmid and tushki for your urgent replies..i know you All are right but i have a question in technical paper the which circuit is more prefreable and why...i know your all logic 100% corect but i coudnt understand the question how can we prefer one circuit another when both doing the same thing..but one thing we have to consider we always conect resistance first then Led in all books in all website we found the same thing but no one use led first then resistance...

one possible reason could be historical -- where the power supply voltages used too be/ could be much higher. Since an LED / Indicator Light is mounted on the front panel, then it was better not to have this high voltage near where a user could accidently touch it directly, or where it could short to a metal chasis. Hence the resistor-to-V+ connection was used, and continues even now as common practise

 

[alexan_e]

its interesting to note that the current is not the same for all in your example. how did you do this...??

Two leds are green (bottom) and two leds are blue(top), for each led color he has connected the resistor in both sides to show that the current is the same , I'm not sure what you find strange in that.

 

[kripacharya]

Two leds are green (bottom) and two leds are blue(top), for each led color he has connected the resistor in both sides to show that the current is the same , I'm not sure what you find strange in that.

ah yes, that'd account for it. I didn't notice the color of the little arrows.

Actually the idea was to connect the meter at various points in the series chain for the 2 different configs, and hence to prove its all the same.
So it is strange then that you would change the value of a component in between these experiments. Thats all.

 

[alexan_e]

Actually the idea was to connect the meter at various points in the series chain for the 2 different configs, and hence to prove its all the same.

I think the point was to prove that the current is the same with different resistor posistioning , not with different meter positioning.
He has shown that the resistor positioning doesn't change the result and showed that with two different type of leds.