2023 · Q72
In experiment #1, a bar magnet is moved towards a conducting wire loop axially, with the magnet's north pole facing the loop. In experiment #2, the same process as in experiment #1 is repeated except that the south pole of the magnet faces the loop. Which one of the following statements is true in this context?
general-sciencephysics-light-electricity
- AThe direction of current in the loop will be of opposite nature in both the experiments.
- BThe direction of current in the loop will be the same in both the experiments.
- CNo current will flow in either of the two experiments.
- DMore current will flow in the loop in experiment #1.
Explanation
By Lenz's law the induced current always opposes the change that produces it. An approaching north pole induces a current whose magnetic field repels the magnet, while an approaching south pole induces a current whose field attracts it, which requires the current to flow in the opposite direction. The currents in the two experiments are therefore of opposite nature. Hence option A.