Rankers Physics

Magnetic Properties of Matter: Practice Problem & Solution

20. A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from: (2018)
The lattice structure of the material of the rod
The magnetic field
The current source
The induced electric field due to the changing magnetic field

Solution Explained:

To solve this problem, we apply the core principles of Magnetic Properties of Matter. Understanding the underlying formula is key to arriving at the correct answer below:

When the diamagnetic rod moves out of the magnetic field, it modifies the magnetic flux through the electromagnet. To maintain the magnetic field and current against the back emf, the current source does extra work, which provides the gained gravitational potential energy.

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