Moment Of Inertia

The period of oscillation of a dipole in a uniform electric field is given by the formula: Where is the period of oscillation, is the moment of inertia, is the dipole moment, and is the electric field. This equation represents simple harmonic motion where the restoring torque is proportional to the angular displacement.

The correct option is (B):

Given:

• Mass of each disc:
• Radius of each disc:
• Six surrounding discs with a central disc

Step 1: Moment of Inertia of a Single Disc

The moment of inertia of a disc about its central axis is:

Step 2: Moment of Inertia of Six Outer Discs

Each outer disc is at a distance from the central axis. Using the parallel axis theorem:

Step 3: Total Moment of Inertia

Since there are 6 outer discs:

Answer: The moment of inertia of the system is (Option B).