E. H. Hall devised an experiment in 1879 to experimentally determine the sign of charge carriers in metals. Using his idea (the Hall Effect), experiments show that the charge carriers in metals are negatively charged (electrons).
Since a positive charge moving in one direction is equivalent in almost all external fields to a negative charge moving in the other direction, we act as if all charge carriers are positive, and write our calculations accordingly. Some exceptions exist, including the Hall Effect. (paraphrased from Section 27-1 of Halliday, David and Robert Resnick, Fundamentals of Physics, New York, New York, John Wiley and Sons, 1970) Tim Finks *********************************************************************** This e-mail message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is strictly prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original e-mail. *********************************************************************** -----Original Message----- From: Jeff Stout [mailto:[EMAIL PROTECTED] Sent: Monday, August 08, 2005 1:12 PM To: 'Protel EDA Discussion List' Subject: RE: [PEDA] Vias. The physics guys usually get things wrong by insisting that charge is carried by electrons. Then they make you do all kinds of mental gymnastics to keep current flow and voltage drops straight. Maybe they can keep it straight in their heads, but I can't. And more to my point, it's not necessary. The trick is NOT to think about what kind of charge is carrying the current, but to do the math "as if" the current flows from positive to negative. The arrows in NPN, PNP, and other schematic symbols semiconductors were specifically drawn to aid in the deciphering of current flow if you think of current the "conventional" (correct) way. You don't even need to think about which way the electrons/holes are flowing. Jeff Stout P.S. I only know of three instances that you should think about electron/hole current, 1) when trying to understand the detains about how semiconducts work, 2) when trying to understand the Hall Effect, 3) when trying to understand electro-magnetics. ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected] ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
