Metal Lattice Simulation
This simulation demonstrates the principle that the resistance of a metal conductor increases with temperature. As temperature rises, the metal ions in the lattice vibrate more vigorously. This increased vibration causes charge carriers (electrons) to collide more frequently with the ions, hindering their movement. As a result, resistance increases and the current flowing through the conductor decreases for the same applied voltage.
At the A-Level, this simulation extends the understanding of current by examining it from a microscopic perspective in terms of mean drift velocity. Instead of viewing current simply as the rate of flow of charge, students learn that electrons in a conductor move slowly on average, with a small net drift in the direction of the electric field. The current depends on how many charge carriers are available and how fast they drift. This is expressed using the equation:
$$I = nAv_dq$$
where is the current, is the number density of charge carriers, is the cross-sectional area of the conductor, is the mean drift velocity of the electrons, and is the charge of each carrier. As temperature increases, more frequent collisions reduce the drift velocity, helping to explain why current decreases even though the charge carriers are still present—linking microscopic behaviour with macroscopic electrical measurements.