{"id":185,"date":"2009-07-27T06:18:07","date_gmt":"2009-07-27T11:18:07","guid":{"rendered":"http:\/\/www.blueraja.com\/blog2\/?p=185"},"modified":"2011-05-03T11:45:33","modified_gmt":"2011-05-03T16:45:33","slug":"how-fast-do-electrons-move-in-a-circuit","status":"publish","type":"post","link":"https:\/\/www.blueraja.com\/blog\/185\/how-fast-do-electrons-move-in-a-circuit","title":{"rendered":"How fast do electrons move in a circuit?"},"content":{"rendered":"\n<p><span class=\"heading\"><a name=\"How_do_electrons_move_so_slowly\"><\/a><\/span><br \/>\n    A professor once told me that electrons moving from a light switch to a lightbulb move towards it at an average of about a millimeter-per-second, which means they take several hours to reach the bulb. But if that&#8217;s true, why does the light turn on instantly when I flip the switch?<\/p>\n<p>The reason is that it&#8217;s the electric field, not the electrons themselves, that transfers energy. Just as north-poles of two magnets will repel each other via their magnetic fields, so will two electrons repel one-another via their electric fields. This repulsion propagates down the wire, with one group of electrons pushing another group of electrons, who in turn push more electrons&#8230;<\/p>\n<p>As a popular analogy, imagine a long skinny tube, just wide enough to hold a ping-pong ball. This tube is completely filled from end-to-end with ping-pong balls. Once everything is set up in your head, imagine forcing another ping-pong ball into the tube at one end. Though the individual ping-pong balls will move only a small amount, the force of each ping-pong ball bumping into the next will propagate quickly all the way down the tube, and at the very end the final ping-pong ball will (almost) immediately be pushed out.<br \/>\n      <img decoding=\"async\" loading=\"lazy\" src=\"http:\/\/www.blueraja.com\/images\/blog\/post22\/ball_in_tube.gif\" width=\"330\" height=\"130\" \/><br \/>\n    Propagating electric fields work in a similar manner, but the electrons are much smaller than ping-pong balls and there are many more of them flying around.<\/p>\n<p> The all-too-common view that electrons are little packets of energy that are somehow created by batteries and &quot;used up&quot; by a lightbulb is completely false. In AC, the voltage continuously goes from positive to negative and back, so, much like someone on an inner tube in a wave-pool, the electrons simply move back and forth on the wire without ever going anywhere (this is why it doesn&#8217;t matter which way you plug things into the wall &#8211; <a href=\"http:\/\/en.wikipedia.org\/wiki\/AC_power_plugs_and_sockets#Polarization\">for the most part<\/a>). In both AC and DC, the energy comes from the movement of the electrons, not the electrons themselves.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A professor once told me that electrons moving from a light switch to a lightbulb move towards it at an average of about a millimeter-per-second, which means they take several hours to reach the bulb. But if that&#8217;s true, why does the light turn on instantly when I flip the switch? The reason is that [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/posts\/185"}],"collection":[{"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/comments?post=185"}],"version-history":[{"count":5,"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/posts\/185\/revisions"}],"predecessor-version":[{"id":246,"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/posts\/185\/revisions\/246"}],"wp:attachment":[{"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/media?parent=185"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/categories?post=185"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.blueraja.com\/blog\/wp-json\/wp\/v2\/tags?post=185"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}