Need help with a Resistor calculation please
 

I have this question and I am wondering if someone can tell me the
formula and how they derived the answer (steps) - it is probably
simple, but I am learning this as I go :

Electronic
1) A simple circuit consists of a current limiting resistor in series
with an LED across a supply voltage of 5VDC. The forward voltage drop
is 1.5VDC and the forward current is 10mA. The series resistor would
have a value of:
a. 1kΩ
b. 500Ω
c. 350Ω
d. 100Ω

Need help with a Resistor calculation please
 

David D ) writes:
I have this question and I am wondering if someone can tell me the
formula and how they derived the answer (steps) - it is probably
simple, but I am learning this as I go :

This is a newsgroup about the repair of electronic equipment.

In what way is your basic question related to repair?

If you'd looked at Mark Zenier's guide to the sci.electronics.*
hierarchy:
ftp://ftp.eskimo.com/u/m/mzenier/seguide9706.txt
you'd likely catch on that this isn't the place to ask such
things, while sci.electronics.basics is.

And of course, this is an example of the damage google is
doing to the newsgroups. It makes it too easy for people to blunder
into the wrong newsgroup.

Michael

Need help with a Resistor calculation please
 

I regret posting it on here. I see you are passionate about this
group, I was hoping I could get an answer quickly and this group has
always been good about replying.



On Aug 14, 10:40 am, (Michael Black) wrote:
David D ) writes:
I have this question and I am wondering if someone can tell me the
formula and how they derived the answer (steps) - it is probably
simple, but I am learning this as I go :

This is a newsgroup about the repair of electronic equipment.

In what way is your basic question related to repair?

If you'd looked at Mark Zenier's guide to the sci.electronics.*
hierarchy:
ftp://ftp.eskimo.com/u/m/mzenier/seguide9706.txt
you'd likely catch on that this isn't the place to ask such
things, while sci.electronics.basics is.

And of course, this is an example of the damage google is
doing to the newsgroups. It makes it too easy for people to blunder
into the wrong newsgroup.

Michael

Need help with a Resistor calculation please
 

"David D" wrote in message
oups.com...
I have this question and I am wondering if someone can tell
me the
formula and how they derived the answer (steps) - it is
probably
simple, but I am learning this as I go :

Electronic
1) A simple circuit consists of a current limiting resistor
in series
with an LED across a supply voltage of 5VDC. The forward
voltage drop
is 1.5VDC and the forward current is 10mA. The series
resistor would
have a value of:
a. 1kΩ
b. 500Ω
c. 350Ω
d. 100Ω

OK you need to conduct 10ma through a resistor with 5 - 1.5
= 3.5 volts across it. Since R = 3.5/.01, you can take it
from there.
Is this a homework assignment? If so and you can not figure
this out, switch majors.

David

Need help with a Resistor calculation please
 

On 14 Aug, 15:30, David D wrote:

I have this question and I am wondering if someone can tell me the
formula and how they derived the answer (steps) - it is probably
simple, but I am learning this as I go :

Electronic
1) A simple circuit consists of a current limiting resistor in series
with an LED across a supply voltage of 5VDC. The forward voltage drop
is 1.5VDC and the forward current is 10mA. The series resistor would
have a value of:
a. 1kΩ
b. 500Ω
c. 350Ω
d. 100Ω

V=IR. If you think folk are gonna do your homework for you, get
serious.

FWIW the q's a bit ambiguous


NT

Need help with a Resistor calculation please
 

In article .com,
David D wrote:
I have this question and I am wondering if someone can tell me the
formula and how they derived the answer (steps) - it is probably
simple, but I am learning this as I go :

Electronic
1) A simple circuit consists of a current limiting resistor in series
with an LED across a supply voltage of 5VDC. The forward voltage drop
is 1.5VDC and the forward current is 10mA. The series resistor would
have a value of:
a. 1k#
b. 500#
c. 350#
d. 100#

The formula for calculating the series resistor value is:-




(Vs-Vf)
R = -------
I

Where R is the resistance in ohms
Vs the supply volts
Vf the forward voltage drop
I the forward current in amps.

--
*The first rule of holes: If you are in one, stop digging!

Dave Plowman London SW
To e-mail, change noise into sound.

1) Don't Multi-post 2) Do your own homework (was: ...Resistor calculation)
 

David D wrote:
[...]I am wondering if someone can tell me the formula

This is not kosher.
http://groups.google.com/groups/sear...g=d&filter= 0

Do it this way if you MUST post it multiple times.
http://www.google.com/search?q=cache...ewsgroups.line

http://groups.google.com/group/sci.electronics.basics/browse_frm/thread/7b7c0624331012bb/9bba213e1c4c044f?q=EVERY-group-*-*-*-*-*-*-*-*-appear+*-proper-answer-*-*-*-given+much-easier-*-*-*-*-*-*-*+*-frowned-on+*-correcting+*-Followup-To-*+*-*-_perfect_-*-*-*-*+*-*-*-too-lazy-*-*-*-*-*-appropriate-*+*-polite-*-mention-*-*-*-*-*-*-*+Just-because-*-*-*-*-*-*-*-*-does-not-mean-*-*-*-*-*-*+mark-*-*-*-*-all-*-groups+*-*-*-*-two-groups-*-*-aren't-*-different
http://groups.google.com/group/sci.electronics.basics/browse_frm/thread/7b7c0624331012bb/3958f18673b5f374?q=EVERY-group-*-*-*-*-*-*-*-*-appear+*-proper-answer-*-*-*-given+much-easier-*-*-*-*-*-*-*+*-frowned-on+*-correcting+*-Followup-To-*+*-*-_perfect_-*-*-*-*+*-*-*-too-lazy-*-*-*-*-*-appropriate-*+*-polite-*-mention-*-*-*-*-*-*-*+Just-because-*-*-*-*-*-*-*-*-does-not-mean-*-*-*-*-*-*+mark-*-*-*-*-all-*-groups+*-*-*-*-two-groups-*-*-aren't-*-different

Need help with a Resistor calculation please
 

On Aug 14, 11:32 am, Meat Plow wrote:

Pay no attention to Michael. There are plenty of people here who would
answer your questions and not attempt to net-nanny you.

Isn't Michael engaged to Malissa Baldwin?

Peter Wieck
Wyncote, PA

1) Don't Multi-post 2) Do your own homework (was: ...Resistor calculation)
 

JeffM ) writes:
David D wrote:
[...]I am wondering if someone can tell me the formula

This is not kosher.
http://groups.google.com/groups/sear...g=d&filter= 0

Wait a minute. I took him to task for posting a basic question in a repair
newsgroup. I think the post in .basics was a result of that. Certainly I
saw it there after I had posted here (and I check .basics before .repair).

The off-topic posts here are becoming as common as the spam.

(And I gave up on .design months ago)

Michael

1) Don't Multi-post 2) Do your own homework (was: ...Resistor calculation)
 

"Michael Black" wrote in message
...
JeffM ) writes:
David D wrote:
[...]I am wondering if someone can tell me the formula

This is not kosher.
http://groups.google.com/groups/sear...g=d&filter= 0

Wait a minute. I took him to task for posting a basic question in a
repair
newsgroup. I think the post in .basics was a result of that. Certainly I
saw it there after I had posted here (and I check .basics before .repair).

The off-topic posts here are becoming as common as the spam.

(And I gave up on .design months ago)

Michael

Much as you would like it otherwise, life is not black and white. It is full
of grey areas, and Usenet newsgroups are one such area. Just because I am a
radio ham, it doesn't mean that I have to talk to other radio hams just
about radio topics. Sometimes, we talk about motor cycles. Or sewage works.
Or the grand Canyon. Such is the way it is also on here. Intelligent
like-minded engineers, sometimes talk among themselves, in one thread
amongst many, about things of mutual interest, which may or may not be
electronics related, and often, even if they are electronic, not related
directly to repair. And sometimes, we all help those who either blunder in
here with a slightly off-topic question, or come here deliberately because
they know that they will get help, as this poster did. Why do you always
have such a cry about it ? It is not a big problem on this group is it ? Or
perhaps you *do* see it as one ? I just see it as a bunch of Usenet
'friends' acting responsibly, and trying to extend that frienship to others,
who might subsequently become regular and valued contributors ...

Honestly, Michael, lighten up a bit.

Arfa

1) Don't Multi-post 2) Do your own homework (was: ...Resistor calculation)
 

On Aug 14, 5:52 pm, "Arfa Daily" wrote:
"Michael Black" wrote in message

...





JeffM ) writes:
David D wrote:
[...]I am wondering if someone can tell me the formula

This is not kosher.
http://groups.google.com/groups/sear...thor=SQ5QHhEAA...

Wait a minute. I took him to task for posting a basic question in a
repair
newsgroup. I think the post in .basics was a result of that. Certainly I
saw it there after I had posted here (and I check .basics before .repair).

The off-topic posts here are becoming as common as the spam.

(And I gave up on .design months ago)

Michael

Much as you would like it otherwise, life is not black and white. It is full
of grey areas, and Usenet newsgroups are one such area. Just because I am a
radio ham, it doesn't mean that I have to talk to other radio hams just
about radio topics. Sometimes, we talk about motor cycles. Or sewage works.
Or the grand Canyon. Such is the way it is also on here. Intelligent
like-minded engineers, sometimes talk among themselves, in one thread
amongst many, about things of mutual interest, which may or may not be
electronics related, and often, even if they are electronic, not related
directly to repair. And sometimes, we all help those who either blunder in
here with a slightly off-topic question, or come here deliberately because
they know that they will get help, as this poster did. Why do you always
have such a cry about it ? It is not a big problem on this group is it ? Or
perhaps you *do* see it as one ? I just see it as a bunch of Usenet
'friends' acting responsibly, and trying to extend that frienship to others,
who might subsequently become regular and valued contributors ...

Honestly, Michael, lighten up a bit.

Arfa- Hide quoted text -

- Show quoted text -

I second Arfa's comments. If the OP comes back repeatedly, that's the
time to make suggestions as to where to go, otherwise, lighten up.

H. R. (Bob) Hofmann

1) Don't Multi-post 2) Do your own homework (was: ...Resistor calculation)
 

On Tue, 14 Aug 2007 21:49:10 -0700 "hr(bob) "
wrote in Message id:
.com:

On Aug 14, 5:52 pm, "Arfa Daily" wrote:
"Michael Black" wrote in message

...





JeffM ) writes:
David D wrote:
[...]I am wondering if someone can tell me the formula

This is not kosher.
http://groups.google.com/groups/sear...thor=SQ5QHhEAA...

Wait a minute. I took him to task for posting a basic question in a
repair
newsgroup. I think the post in .basics was a result of that. Certainly I
saw it there after I had posted here (and I check .basics before .repair).

The off-topic posts here are becoming as common as the spam.

(And I gave up on .design months ago)

Michael

Much as you would like it otherwise, life is not black and white. It is full
of grey areas, and Usenet newsgroups are one such area. Just because I am a
radio ham, it doesn't mean that I have to talk to other radio hams just
about radio topics. Sometimes, we talk about motor cycles. Or sewage works.
Or the grand Canyon. Such is the way it is also on here. Intelligent
like-minded engineers, sometimes talk among themselves, in one thread
amongst many, about things of mutual interest, which may or may not be
electronics related, and often, even if they are electronic, not related
directly to repair. And sometimes, we all help those who either blunder in
here with a slightly off-topic question, or come here deliberately because
they know that they will get help, as this poster did. Why do you always
have such a cry about it ? It is not a big problem on this group is it ? Or
perhaps you *do* see it as one ? I just see it as a bunch of Usenet
'friends' acting responsibly, and trying to extend that frienship to others,
who might subsequently become regular and valued contributors ...

Honestly, Michael, lighten up a bit.

Arfa- Hide quoted text -

- Show quoted text -

I second Arfa's comments. If the OP comes back repeatedly, that's the
time to make suggestions as to where to go, otherwise, lighten up.

Thirded. A far greater problem has been all the spam emanating from
Google. Off topic posts are no big deal, and at least the OP's question
was electronics related.