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1) A coil of wire is arranged with its plane perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time Δt then what is the emf induced in the coil ? a. ωB/r22-r12/Δt b. ωB(r2-r1)2/Δt c. ωB(r22-r12)/Δt d. ωB(r22+r12)/Δt
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2) Self-inductance of a long solenoid is______________? a. μoN2A b. μoN2/A c. μoN2 d. BA
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3) The alternating current has frequency of 106 Hz in such a way that time period for completion of cycle is_______________? a. 1Hzs b. 1.5Hzs c. 106sec d. 1sec
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4) Self inductance of a coil depends upon________________? a. current flowing b. number of turns per unit length c. voltage produce d. all
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5) Energy stored in a magnetic field is given by______________? a. LI2 b. L2I/2 c. LI2/2 d. IL2
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6) For electroplating we use_________________? a. A D.C source b. an A.C source c. any source d. all of the above
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7) The only difference between construction of D.C generator and A.C generator is that of_______________? a. carbon brushes b. coil c. commutator d. magnetic field
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8) If the secondary coil has Ns turns and the primary Np turns the relation between secondary and primary voltages is given by_____________? a. Vs/Vp = Np/Ns b. Vs/Vp = Ns/Np c. Vp/Vs = Ns/Np d. Vp/Vs = Np/Ns
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9) A metal rod of 25 cm length is moving at a speed of 0.5/sec in direction perpendicular to 0.25T magnetic field. Emf produced in the rod is_____________? a. 0 volt b. 3.125 volt c. 31.25 volt d. 0.03125 volt
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10) The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core_______________? a. Decreases the resistance of the solenoid b. Reduces the effect of eddy current c. Improves the flux linkage between the turns of the coil d. Increases the mutual inductance between the solenoid and the core
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