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# A square loop of copper wire is initially placed perpendiclar to the lines of a constant magnetic field of 5\times10^3 T.The area enclosed by the loop

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A square loop of copper wire is initially placed perpendiclar to the lines of a constant magnetic field of $$\displaystyle{5}\times{10}^{{3}}$$ T.The area enclosed by the loop is 0.2 square meter. the loopis then turned through an angle $$\displaystyle{90}^{\circ}$$ so thatthe plane of the loop is parallel to the field lines. the turntakes 0.1 second. what is the average emf induced in the loop during the turn?

2021-02-19
$$\displaystyle{E}_{{{a}{v}{g}}}=-{N}{\frac{{\triangle\phi}}{{\triangle{t}}}}$$
N is number of turns of loop = 1
$$\displaystyle\triangle\phi$$ is change of flux linked with the loop
$$\displaystyle\triangle{t}$$ is time in which the change of flux has taken place
$$\displaystyle\phi={B}{A}={5}\times{10}^{{3}}\times{0.2}={1}\times{10}^{{3}}$$ when plane of loop is perpendicular tofield $$\displaystyle\phi={0}$$ when the plane of loop is parallel to field.
$$\displaystyle{E}={1}\times{\frac{{{10}^{{3}}}}{{{0.1}}}}={1}\times{10}^{{4}}$$ v
The negative sign in formula simply shows the direction of induced emf is such that it opposes the change influx according to Lenz's Law.