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A current of `7*0A` is flowing in a plane circular coil of radius `1*0cm` having 100 turns. The coil is placed in a uniform magnetic field of `0*2Wb//m^2`. If the coil is free to rotate, what orientation would correspond to its (i) stable equilibrium and (ii) unstable equilibrium? Calculate potential energy of the coil in the two cases. |
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Answer» Here, `I=7*0A, r=1*0cm=10^-2m`, `N=100, B=0*2Wb//m^2` `M=NIA=Nipir^2` `=100xx7*0xx22/7(10^-2)^2=0*22Am^2` (i) Stable equilibrium corresponds to `theta=0^@` i.e. `vecM` parallel to `vecB`. `u_(min)=-MBcos 0^@=0*22xx0*2xx1` `=-0*044J` (ii) unstable equilibrium corresponds to `vecM` antiparallel to `vecB`. P.E. is maximum `u_(max.)=-MB cos 180^@=-0*22xx0*2xx(-1)` `=0*044J` |
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