A flat dielectric disc of radius R carries an excess charge on its surface. The surface charge density is σ. The disc rotates about an a × is perpendicular to its plane passing through the center with angular velocity ω. Find the magnitude of the torque on the disc if it is placed in a uniform magnetic field whose strength is B which is directed perpendicular to the a × is of rotation(a)\(\frac{1}{4}\)σωπ BR(b)\(\frac{1}{4}\) σωπ BR2 (c) \(\frac{1}{4}\) σωπ BR3(d) \(\frac{1}{4}\)σωπ BR4

A flat dielectric disc of radius R carries an excess charge on its sur

1.	A flat dielectric disc of radius R carries an excess charge on its surface. The surface charge density is σ. The disc rotates about an a × is perpendicular to its plane passing through the center with angular velocity ω. Find the magnitude of the torque on the disc if it is placed in a uniform magnetic field whose strength is B which is directed perpendicular to the a × is of rotation(a)\(\frac{1}{4}\)σωπ BR(b)\(\frac{1}{4}\) σωπ BR2 (c) \(\frac{1}{4}\) σωπ BR3(d) \(\frac{1}{4}\)σωπ BR4
Answer» Correct answer is (d) \(\frac{1}{4}\)σωπ BR⁴

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