A bar magnet is dropped vertically through a long piece of copper pipe. What eff

Question

A bar magnet is dropped vertically through a long piece of copper pipe. What effect does the falling magnet have on the pipe? Select all that apply. The falling magnet... has no effect on the copper pipe. causes the copper pipe to produce a magnetic field. causes the copper pipe to acquire a net change. causes an electric current to flow in the copper pipe. What effect does the presence of the copper pipe have on the magnet? Select all that apply. The copper pipe... is attracted to and sticks to the magnet. causes the magnet to fall more slowly. has no effect on the magnet. causes the magnet to fall more quickly.

Explanation / Answer

Again this is due to electromagnetic induction.  The falling magnet induces current in the metal tube (but not the plastic one) because a particular spot on the tube and below the magnet first sees an increasing magnetic field intensity as the magnet approaches and then a decreasing field intensity as the magnetic moves away from it.  The induced current circulates around the perimeter of the tube and in many respects acts like an electromagnet, producing a magnetic field of its own (recall moving charges generate magnetic fields).  This magnetic is pointed in the opposite direction to that of the falling magnet.  This results in a repulsive force that acts to push the magnet up, like trying to bring the north poles of two magnets close together.  The net force on the falling magnet is less than that of gravity and so the magnet falls more slowly in the metal tube.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.