22. A magnet approaching a coil induces an emf in the coil. This is an example o

Question

22. A magnet approaching a coil induces an emf in the coil. This is an example of a) Coulomb's law. b) Faraday's law. c) Gauss's law. d) Kirchoff?s laws. e) Ampere's law. Find the magnitude of the emf 23. The current through a 0.25-H inductor is given as a function of time by: produced by the inductor at t = 0.29 s. a) 1.0 V b) 1.8V c) 2.2V d) 3.6V e) 4.2V 24. A 45.0-mH inductor is connected to a sinusoidal emf, which has a frequency of 400.0 Hz and an amplitude of 20.0 V. [There is no resistance or capacitance in this circuit.] What is the amplitude of the current oscillations? a) 177 mA b) 622 mA c) 1.11 A d) 83.3 A e) 444 A

Explanation / Answer

22] Faraday's Law

23] The emf producd by the inductor,v=Ldi/dt

= 0.25* d/dt[4.4A+7.2A/s2 ]t2

   = 0.25*2t[4.4A+7.2A/s2 ]=0.25*2*0.29[11.6]=1.8V

24] Given:

Frequency,f= 400Hz

Amplitude,A=20V

Inductance,L= 45mH

Resistance of inductanc=Lw=L*2*3.14*f= 113.04ohms

V=IR

I= V/R=20v/113.04 ohms= 0.177A=177mA

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