📄 06voltage and current in a practical circuit basic concepts of electricity.mht
字号:
From: <由 Windows Internet Explorer 7 保存>
Subject: Voltage and current in a practical circuit : BASIC CONCEPTS OF ELECTRICITY
Date: Tue, 18 Nov 2008 11:34:55 +0800
MIME-Version: 1.0
Content-Type: multipart/related;
type="text/html";
boundary="----=_NextPart_000_00C1_01C94971.ADB56C50"
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579
This is a multi-part message in MIME format.
------=_NextPart_000_00C1_01C94971.ADB56C50
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Content-Location: http://www.allaboutcircuits.com/vol_1/chpt_1/6.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" =
"http://www.w3c.org/TR/1999/REC-html401-19991224/loose.dtd">
<HTML xml:lang=3D"en" =
xmlns=3D"http://www.w3.org/1999/xhtml"><HEAD><TITLE>Voltage and current =
in a practical circuit : BASIC CONCEPTS OF ELECTRICITY</TITLE>
<META content=3D"" name=3Dkeywords>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
<META http-equiv=3DContent-Style-Type content=3Dtext/css><LINK=20
href=3D"http://www.allaboutcircuits.com/styles/style.css" =
type=3Dtext/css=20
rel=3Dstylesheet><LINK media=3Dprint=20
href=3D"http://www.allaboutcircuits.com/styles/print.css" =
type=3Dtext/css=20
rel=3Dstylesheet><LINK href=3D"/favicon.ico" rel=3D"shortcut icon">
<SCRIPT src=3D"http://www.allaboutcircuits.com/scripts/se_hilite.js"=20
type=3Dtext/javascript></SCRIPT>
<SCRIPT src=3D"http://www.allaboutcircuits.com/scripts/worksheets.js"=20
type=3Dtext/javascript></SCRIPT>
<SCRIPT type=3Dtext/javascript>
Hilite.elementid =3D "main";
</SCRIPT>
<LINK title=3D"All About Circuits Forum RSS Feed"=20
href=3D"http://forum.allaboutcircuits.com/external.php?type=3DRSS2"=20
type=3Dapplication/rss+xml rel=3Dalternate><LINK=20
title=3D"All About Circuits Blog RSS Feed"=20
href=3D"http://forum.allaboutcircuits.com/blog_external.php"=20
type=3Dapplication/rss+xml rel=3Dalternate>
<META content=3D"MSHTML 6.00.6000.16735" name=3DGENERATOR></HEAD>
<BODY><!-- start container -->
<DIV id=3Dcontainer><!-- start header -->
<DIV id=3Dheader><!-- start logo --><SPAN class=3Dlogo><A=20
title=3D"All About Circuits : Complete guide to Electric Circuits" =
accessKey=3D1=20
href=3D"http://www.allaboutcircuits.com/">All About Circuits<EM=20
title=3D"All About Circuits : Complete guide to Electric =
Circuits"> </EM></A>=20
</SPAN><!-- end logo -->
<DIV id=3Dheaderright></DIV></DIV><!-- end header --><!-- start nav -->
<UL class=3Dxoxo id=3Dnav>
<LI><A title=3D"Volume I - DC"=20
href=3D"http://www.allaboutcircuits.com/vol_1/index.html">Vol. I - =
DC</A>=20
<LI><A title=3D"Volume II - AC"=20
href=3D"http://www.allaboutcircuits.com/vol_2/index.html">Vol. II - =
AC</A>=20
<LI><A title=3D"Volume III - Semiconductors"=20
href=3D"http://www.allaboutcircuits.com/vol_3/index.html">Vol. III -=20
Semiconductors</A>=20
<LI><A title=3D"Volume IV - Digital"=20
href=3D"http://www.allaboutcircuits.com/vol_4/index.html">Vol. IV - =
Digital</A>=20
<LI><A title=3D"Volume V - Reference"=20
href=3D"http://www.allaboutcircuits.com/vol_5/index.html">Vol. V - =
Reference</A>=20
<LI><A title=3D"Volume VI - Experiments"=20
href=3D"http://www.allaboutcircuits.com/vol_6/index.html">Vol. VI -=20
Experiments</A>=20
<LI><A title=3D"Test your knowledge! Quiz yourself"=20
=
href=3D"http://www.allaboutcircuits.com/worksheets/index.html">Worksheets=
</A>=20
<LI><A title=3D"Read our member's blogs"=20
href=3D"http://forum.allaboutcircuits.com/blog.php">Blogs</A>=20
<LI><A title=3D"Join our electronics forum!"=20
href=3D"http://forum.allaboutcircuits.com/">Forums</A> </LI></UL><!-- =
end nav --><!-- start contentWrap -->
<DIV id=3DcontentWrap><!-- start sidebar -->
<DIV id=3Dsidebar><!-- start search form -->
<DIV id=3Dsearchbox><!-- Google CSE Search Box Begins -->
<FORM id=3Dsearchbox_006978388026519765659:hg719j5vhl8=20
action=3Dhttp://www.allaboutcircuits.com/scripts/search.html><INPUT =
type=3Dhidden=20
value=3D006978388026519765659:hg719j5vhl8 name=3Dcx> <INPUT =
type=3Dhidden=20
value=3DFORID:9 name=3Dcof> <LABEL for=3Ds>Search this =
site</LABEL><BR><INPUT id=3Ds=20
accessKey=3D3 name=3Dq> <INPUT id=3Dsearch type=3Dsubmit value=3DGo =
name=3Dsa> </FORM><!-- Google CSE Search Box Ends --></DIV><!-- end =
search form --><B>Table=20
of Contents:</B>
<UL class=3Dxoxo>
<LI><A title=3D"Page 1: Static electricity"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/1.html">Static=20
electricity</A>
<LI><A title=3D"Page 2: Conductors, insulators, and electron flow"=20
=
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/2.html">Conductors, =
insulators, and electron flow</A>
<LI><A title=3D"Page 3: Electric circuits"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/3.html">Electric=20
circuits</A>
<LI><A title=3D"Page 4: Voltage and current"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/4.html">Voltage =
and=20
current</A>
<LI><A title=3D"Page 5: Resistance"=20
=
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/5.html">Resistance</=
A>
<LI><A title=3D"Page 6: Voltage and current in a practical circuit"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/6.html">Voltage =
and current=20
in a practical circuit</A>
<LI><A title=3D"Page 7: Conventional versus electron flow"=20
=
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/7.html">Conventional=
versus=20
electron flow</A>
<LI><A title=3D"Page 8: Contributors"=20
=
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/8.html">Contributors=
</A>
<LI><A title=3D"Back to BASIC CONCEPTS OF ELECTRICITY Index"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/index.html">Back =
to Chapter=20
Index</A></LI></UL><BR><B>Related Worksheets</B>
<UL>
<LI><A=20
=
href=3D"http://www.allaboutcircuits.com/worksheets/thev.html">Th\'evenin'=
s,=20
Norton's, and Maximum Power Transfer =
theorems</A></LI></UL><BR><B>Recently=20
Viewed:</B>
<UL id=3Dside-recent>
<LI><A title=3D"Resistance : BASIC CONCEPTS OF ELECTRICITY"=20
=
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/5.html">Resistance</=
A>
<LI><A title=3D"Voltage and current : BASIC CONCEPTS OF ELECTRICITY"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/4.html">Voltage =
and=20
current</A>
<LI><A title=3D"Electric circuits : BASIC CONCEPTS OF ELECTRICITY"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/3.html">Electric=20
circuits</A></LI></UL></DIV><!-- end sidebar --><!-- start copy -->
<DIV id=3Dmain>
<UL class=3Dtabs>
<LI><A class=3Dprint title=3D"Print this page - printer friendly"=20
onclick=3Dwindow.print();=20
=
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/6.html#">Print</A>=20
<LI><A class=3Dpdf title=3D"Download in PDF format"=20
href=3D"http://www.allaboutcircuits.com/pdf/DC.pdf">PDF</A> <BR><!-- =
AddThis Bookmark Button BEGIN --><A=20
onclick=3D"addthis_url =3D location.href; addthis_title =3D =
document.title; return addthis_click(this);"=20
href=3D"http://www.addthis.com/bookmark.php" target=3D_blank><IMG =
height=3D16=20
alt=3D"AddThis Social Bookmark Button"=20
src=3D"http://s9.addthis.com/button1-bm.gif" width=3D125 =
border=3D0></A>
<SCRIPT type=3Dtext/javascript>var addthis_pub =3D =
'GFYGCMPH6Z132X8G';</SCRIPT>
<SCRIPT src=3D"http://s9.addthis.com/js/widget.php?v=3D10"=20
type=3Dtext/javascript></SCRIPT>
<!-- AddThis Bookmark Button END --></LI></UL>
<DIV class=3Dmainnav><A title=3D"Volume I - DC"=20
href=3D"http://www.allaboutcircuits.com/vol_1/index.html">Volume I - =
DC</A> =BB <A=20
title=3D"BASIC CONCEPTS OF ELECTRICITY"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/index.html">BASIC =
CONCEPTS OF=20
ELECTRICITY</A> =BB </DIV>
<H1>Voltage and current in a practical circuit</H1>
<DIV id=3Dgoogle-ads>
<SCRIPT type=3Dtext/javascript><!--
google_ad_client =3D "pub-6110766095769513";
/* AAC 468x60, created 9/10/08 */
google_ad_slot =3D "2521151115";
google_ad_width =3D 468;
google_ad_height =3D 60;
//-->
</SCRIPT>
<SCRIPT src=3D"http://pagead2.googlesyndication.com/pagead/show_ads.js"=20
type=3Dtext/javascript>
</SCRIPT>
</DIV>
<P>Because it takes energy to force electrons to flow against the =
opposition of=20
a resistance, there will be voltage manifested (or "dropped") between =
any points=20
in a circuit with resistance between them. It is important to note that =
although=20
the amount of current (the quantity of electrons moving past a given =
point every=20
second) is uniform in a simple circuit, the amount of voltage (potential =
energy=20
per unit charge) between different sets of points in a single circuit =
may vary=20
considerably: </P>
<P><IMG src=3D"http://sub.allaboutcircuits.com/images/00030.png"> </P>
<P>Take this circuit as an example. If we label four points in this =
circuit with=20
the numbers 1, 2, 3, and 4, we will find that the amount of current =
conducted=20
through the wire between points 1 and 2 is exactly the same as the =
amount of=20
current conducted through the lamp (between points 2 and 3). This same =
quantity=20
of current passes through the wire between points 3 and 4, and through =
the=20
battery (between points 1 and 4). </P>
<P>However, we will find the voltage appearing between any two of these =
points=20
to be directly proportional to the resistance within the conductive path =
between=20
those two points, given that the amount of current along any part of the =
circuit's path is the same (which, for this simple circuit, it is). In a =
normal=20
lamp circuit, the resistance of a lamp will be much greater than the =
resistance=20
of the connecting wires, so we should expect to see a substantial amount =
of=20
voltage between points 2 and 3, with very little between points 1 and 2, =
or=20
between 3 and 4. The voltage between points 1 and 4, of course, will be =
the full=20
amount of "force" offered by the battery, which will be only slightly =
greater=20
than the voltage across the lamp (between points 2 and 3). </P>
<P>This, again, is analogous to the water reservoir system: </P>
<P><IMG src=3D"http://sub.allaboutcircuits.com/images/00031.png"> </P>
<P>Between points 2 and 3, where the falling water is releasing energy =
at the=20
water-wheel, there is a difference of pressure between the two points,=20
reflecting the opposition to the flow of water through the water-wheel. =
From=20
point 1 to point 2, or from point 3 to point 4, where water is flowing =
freely=20
through reservoirs with little opposition, there is little or no =
difference of=20
pressure (no potential energy). However, the rate of water flow in this=20
continuous system is the same everywhere (assuming the water levels in =
both pond=20
and reservoir are unchanging): through the pump, through the =
water-wheel, and=20
through all the pipes. So it is with simple electric circuits: the rate =
of=20
electron flow is the same at every point in the circuit, although =
voltages may=20
differ between different sets of points. </P>
<DIV class=3Dbotnav align=3Dcenter><A title=3D"Discuss this topic on our =
forums"=20
href=3D"http://forum.allaboutcircuits.com/">Discuss this =
topic</A> | <A=20
title=3D"Find any errors or typos? Help us correct them"=20
href=3D"http://forum.allaboutcircuits.com/forumdisplay.php?f=3D11">Feedba=
ck</A>=20
<A title=3D"Previous page in =
chapter"=20
href=3D"http://www.allaboutcircuits.com/vol_1/chpt_1/5.html">=ABPrevious =
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -