What happens when a current flows through a conductor? In HSC Physics students learn that the resistance of a conductor is due to the collisions of the conduction electrons with the atoms in the conductor. These collisions transfer energy from the electrons to an increase in the vibrational energy of the atoms causing an increase in temperature of the conductor. What would be an estimate of the drift speed of conduction electrons through a metal; 1 mm/s, 1 m/s, 1000 m/s or 1,000,000 m/s? The answer is 1 mm/s. When a light globe is switched on an electric field is sent along the connecting wire at a speed of about one-third of the speed of light and this field pushes electrons at the far end of the wire through first, so the globe appears to glow immediately. Quantum mechanics also teaches us that electrons behave as waves. The electron waves are scattered by the irregularly spaced atoms in the conductor which are displaced from a regular pattern due to their thermal vibration.
Physics and Mathematics
What are the concepts in Physics and Mathematics that students find difficult? In this blog I will post tutorial points that I hope will stimulate thinking and so broaden the knowledge and understanding of students allowing them to write thorough examination responses. Tutorial sheets, structured from a student's point of view, will be posted on the HSC, IB and university level topics of Relativity, Electromagnetism, Mechanics, Quantum Physics and Calculus. The overall purpose of these pages is to encourage and promote learning in Physics and Mathematics and so open new horizons in learning.