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Three charges q, q, and -2q are fixed on the vertices of an equilateral triangular plate of edge length a. This plate is in equilibrium between two very large plates having surfaces charge density `sigma_1 and sigma_2`, respectively. Find the time period of small anglular oscillations about an axis passing through its centroid and perpendicular to the plane. Moment of inertia of the system about this axis is l.A. `2pi sqrt((epsilon_0l)/(qa|sigma_1-sigma_2|)`B. `2pi sqrt((epsilon_0l)/(2qa|sigma_1-sigma_2|)`C. `2pi sqrt((2epsilon_0l)/(sqrt3qa|sigma_1-sigma_2|)`D. `2pi sqrt((2epsilon_0l)/(qa|sigma_1-sigma_2|)` |
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Answer» Correct Answer - C Net dipole moment `=sqrt(3)qa` `r=-sqrt(3)qa([sigma_(1)-sigma_(2)]theta)/(2epsilon_(0))=1a` `(sqrt(3)qa|sigma_(1)-sigma_(2)])/(2epsilon_(0))=l((2pi)/(T))` `T=2pisqrt(((2epsilon_(0)l))/(sqrt(3)qa|sigma_(1)-sigma_(2)])` |
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