Talk:Farad

From Wikipedia, the free encyclopedia

WikiProject Physics This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Start This article has been rated as start-Class on the assessment scale.
??? This article has not yet received an importance rating within physics.

Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.

Contents

[edit] Picofarad

In the picofarad article, there is the following statement : "the picofarad is the smallest measurable unit of electrical capacitance". I tagged it as dubious. Please confirm. --Edcolins 19:42, August 21, 2005 (UTC)

It's rubbish. I removed it. --Heron 20:25, 21 August 2005 (UTC)
Thanks! --Edcolins 20:46, August 21, 2005 (UTC)

[edit] Femtofarad

What about redirecting "femtofarad" to "farad"? Or creating a proper article? --Edcolins 20:48, August 21, 2005 (UTC)

By all means create a redirect. I don't know any anecdotes about femtofarads, so I can't help you to create a proper article! Somebody can convert the redirect to an article later on, if they want to. --Heron 20:55, 21 August 2005 (UTC)
Done. --Edcolins 21:12, August 21, 2005 (UTC)


[edit] Usage in car stereo equipment

I think the mention of the 1-farad capacitors for 1000W car-stereos is rather non-encyclopedic. And what is meant by "sufficient to drive"? Do these capacitors generate power? I suspect that the real answer is that by trial-and-error, someone has figured out that 1F capacitors can be used to stabilize the cars electrical system while playing typical (loud) music. That is, during the most powerful bass-bursts, the capacitor can feed current to the amplifier, and then be recharged until the next beat comes.

For how long?
They mention a Farad is a very alrge unit, but how large? They mention they can power 1,000 watt stereo, but for how long? Nnfolz 16:29, 9 February 2006 (UTC)
Not very, 1 farad means that when charged to 12V it will have 12 colombs of charge. I cba to do the calculus to work out how much energy that represents but it will be less than 144 (12*12) joules. so we are talking figures on the order of a tenth of a second or so. Still i can see it making quite a difference to heavy bass beats. Plugwash 01:22, 12 November 2006 (UTC)
I don't know what was removed but if putting in that femtofarad capacitors are used in integrated circuits, then putting in that 1 or more farad capacitors are used in car sound systems should be acceptable as a perspective tool. (A one Farad cap is about the size of a tennis ball can.) I've been researching capacitors as an alternative to batteries (yes I know that caps have 100x less power density/weight ration than bats), and I've seen these caps all over the net. It took me a while to figure out what (most) people use them for. I almost want to shell out the $100 for one so I can use it to explode walnuts and such :), although that would probably break the cap eventually. :(
Tiki God 15:29, 15 July 2007 (UTC)

[edit] SI multiples is unnecessary

the SI multiples table is ridiculously unnecessary. Do I have to explain why? Fresheneesz 01:08, 23 May 2006 (UTC)

I concur, it's just silly. Pdbailey 00:49, 26 September 2006 (UTC)
I agree. I just removed it. Edurant 05:42, 14 March 2007 (UTC)

[edit] Caps pic

I have added a picture of a 1F capacitor. If it is preferable to the existing one, maybe the existing one can be removed. —Preceding unsigned comment added by 128.171.10.147 (talk) 02:50, 27 September 2007 (UTC)

How does Image:Supercaps_1.5F_capacitors.jpg‎ swing you? They are 1.5F, not 1F, though. - Keith D. Tyler (AMA) 19:37, 26 January 2007 (UTC)

I'd make the comment that the "puniness" that some complain of might not a function of capacitance but also rated voltage. Perhaps these people are really talking about the ability of the capacitor to store energy (0.5*C*V^2), which in turn is related to physical size and the amount of damage it can do when discharged? When discharged a 1pF capacitor charged to 1MV will do as much damage as a 1F capacitor charged to 1V, based on available energy. In fact the 1pF capacitor will probably discharge faster giving a higher instantaneous power. Maybe the complainer wants a pic of one of those high voltage capacitor banks used to power fusion reactors? :-) John Dalton 00:56, 14 March 2007 (UTC)

[edit] Added definition back

I'm not sure why the definition with equivalent units was removed a few days ago without a descriptive comment or Talk entry. I think this is necessary and useful information, and it is included in similar articles, such as Volt. I added it back with some tweaks. Edurant 05:44, 14 March 2007 (UTC)

[edit] Picture Detail

The description on the second picture which has the words "tricked-out car," has to be unnecessary. Re-wording it with "...fills the back seat of a car." Under most situations, people know that stock cars don't normally have large capacitors for a stock stereo (i.e. custom stereo systems = custom parts, stock stereo = stock parts). --Specter01010 02:53, 19 April 2007 (UTC)

[edit] Picture accurate?

That looks VERY small for a 1F capacitor —Preceding unsigned comment added by 86.29.81.44 (talk) 07:04, 16 April 2008 (UTC)

[edit] alternate definition

I changed

  • "an alternate definition is that a farad is one ampere-second of charge at one volt" to
  • "an alternate definition is that a farad is the amount of capacitance that requires one second for a one ampere flow of charge to change the voltage by one volt."

I hope this is more understandable. (But I would prefer a cited definition from a good source). --76.209.28.72 18:51, 26 June 2007 (UTC)