Physics
Physics
Problem
Two coaxial circular coils C₁ and C₂ are placed close to each other. The current in C₂ decreases with time and, as seen by an observer looking along the common axis, the current in C₂ is clockwise. The direction of the induced current in C₁, as viewed by the same observer, is a) b) c) d)Intuitive explanation
This is about electromagnetic induction and Lenz's law—the key insight is that a changing magnetic field in one coil induces a current in the nearby coil that opposes that change. Since the current in C₂ is decreasing, its magnetic field through C₁ is weakening. The induced current in C₁ must flow in a direction that creates a magnetic field pointing the same way as C₂'s original field, trying to "prop up" the fading flux. Use the right-hand rule to translate current direction into field direction, then apply Lenz's law to find which way C₁'s current must flow.
Intuitive explanation
This is about electromagnetic induction and Lenz's law—the key insight is that a changing magnetic field in one coil induces a current in the nearby coil that opposes that change. Since the current in C₂ is decreasing, its magnetic field through C₁ is weakening. The induced current in C₁ must flow in a direction that creates a magnetic field pointing the same way as C₂'s original field, trying to "prop up" the fading flux. Use the right-hand rule to translate current direction into field direction, then apply Lenz's law to find which way C₁'s current must flow.