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A circular coil of radius 10 cm, 500 turns and resistance 2 Omega is placed with its plane perpendicular to the horizontal component of the earth’s magnetic field. It is rotated about its vertical diameter through 180^@ in 0.25 s. Estimate the magnitudes of the emf and current induced in the coil. Horizontal component of the earth’s magnetic field at the place is 3.0 ×x 10^(-5) T. |
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Answer» Solution :Initial flux through the coil, `Phi_(B("initial")) = BA cos theta ` `=3.0 xx 10^(-5) xx (pi xx 10^(-2)) xx cos 0^@` `=3pi xx 10^(-7)` Wb Final flux after the rotation. `Phi_(B("final")) = 3.0 xx 10^(-5) xx (pi xx 10^(-2)) xx cos 180^@ ` `= - 3pi xx 10^(-7)` Wb Therefore, estimated value of the induced emf is , `epsi =N (DELTA Phi)/(Deltat)` `= 500 xx (6 pi xx 10^(-7)) //0.25` `= 3.8 xx 10^(-3) V` `I = epsi//R = 1.9 xx 10^(-3) A ` Note that the magnitudes of `epsi` and I are the estimated values. Their INSTANTANEOUS values are different and depend upon the speed of rotation at the PARTICULAR instant. |
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