A compass needle initially at to a uniform magnetic field experiences an initial…

PHYSICS · Single correct · CBSE · Physics · Magnetism and Matter · Magnetism and Matter

Problem

A compass needle initially at 20∘20^{\circ} to a uniform magnetic field experiences an initial angular acceleration α0\alpha_{0}. If the magnitude of the external magnetic field is suddenly doubled while the needle’s moment of inertia and magnetic moment remain unchanged, which statement best describes the needle’s new initial angular acceleration αnew\alpha_{\text{new}}? (a) αnew=2 α0\alpha_{\text{new}} = \sqrt{2}\,\alpha_{0} (b) αnew=2α0\alpha_{\text{new}} = 2\alpha_{0} (c) αnew=4α0\alpha_{\text{new}} = 4\alpha_{0} (d) αnew=12α0\alpha_{\text{new}} = \dfrac{1}{2}\alpha_{0}

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