8.02 Lecture Notes - Lecture 1: Joule Heating, Eddy Current (Comics), Curve
Document Summary
At time t: the gure above right shows a side view of a section of a very long solenoid with radius r carrying current i with magnetic eld pointing up. The gure below right shows a top view of the electric eld inside the solenoid at a radius r and the direction of the magnetic eld. In the solenoid, the current is decreasing in time. If c is a stationary closed curve and s is a surface spanning c then. The changing magnetic ux through s induces a non-electrostatic electric eld whose line integral around c is non-zero. Induced current, torque, or force is always directed to oppose the change that caused it. The magnetic induces currents in the metal that dissipate the energy through joule heating. Current is induced counter-clockwise (out from the center) The magnet induces current in the metal that dissipate the energy through joule heating.
B-field lines run from the left to right through both the loop and solenoid)