Lenz's Law, Eddy Currents & Induced Electric Field
An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil?
Show answer and solution
Answer: (a)
- A moving electron is a current (opposite to its motion), so it sets up a magnetic field through the coil.
- As the electron approaches, the flux through the coil increases; after it passes, the flux decreases.
- By Lenz's law the induced current has one direction while flux increases and the opposite while it decreases.
- So the current reverses as the electron goes past, answer (a).