JEE Advanced 2015 Paper 2 Physics Q18

Physics · Moving Charges & Magnetism

Problem

PARAGRAPH 1 In a thin rectangular metallic strip a constant current II flows along the positive xx-direction, as shown in the figure. The length, width and thickness of the strip are ll, ww and dd, respectively. A uniform magnetic field B⃗\vec B is applied on the strip along the positive yy-direction. Due to this, the charge carriers experience a net deflection along the zz-direction. This results in accumulation of charge carriers on the surface PQRSPQRS and appearance of equal and opposite charges on the face opposite to PQRSPQRS. A potential difference along the zz-direction is thus developed. Charge accumulation continues until the magnetic force is balanced by the electric force. The current is assumed to be uniformly distributed on the cross section of the strip and carried by electrons. Consider two different metallic strips (1 and 2) of same dimensions (length ll, width ww and thickness dd) with carrier densities n1n_1 and n2n_2, respectively. Strip 1 is placed in magnetic field B1B_1 and strip 2 is placed in magnetic field B2B_2, both along positive yy-directions. Then V1V_1 and V2V_2 are the potential differences developed between KK and MM in strips 1 and 2, respectively. Assuming that the current II is the same for both the strips, the correct option(s) is (are)

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