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(a) How long does it take the solenoid currentto reach 0.632 times its maximum v

ID: 1672243 • Letter: #

Question

(a) How long does it take the solenoid currentto reach 0.632 times its maximum value?
1 s

(b) Determine the average back emf caused by the self-inductance ofthe solenoid during this interval. The magnetic field produced bythe solenoid at the location of the coil is one-half as strong asthe field at the center of the solenoid.
2 V

(c) Determine the average rate of change in magnetic flux througheach turn of the coil during the stated interval.
3 V

(d) Find the magnitude of the average induced current in thecoil.
4 A An 800-turn wire coil of resistance 24.0 ohm is placed on top of a 6.60 cm longsolenoid with N1 = 12200 turns, as in the figure below. Both coil andsolenoid have cross-sectional areas of 1.31 x 10^-4 m^2. (a) How long does it take the solenoid currentto reach 0.632 times its maximum value? 1 s (b) Determine the average back emf caused by the self-inductance ofthe solenoid during this interval. The magnetic field produced bythe solenoid at the location of the coil is one-half as strong asthe field at the center of the solenoid. 2 V (c) Determine the average rate of change in magnetic flux througheach turn of the coil during the stated interval. 3 V (d) Find the magnitude of the average induced current in thecoil. 4 A

Explanation / Answer


(a)
   the current in the solenoid reaches
   I = 0.632 Imax in the time
   t =
     = L / R
   where
   L = o N2 A / a
      = .......... H
   t = ........ s
(b)
   the change in thesolenoid current during thistime is
   I = 0.632 Imax - 0
        = 0.632 (V /R)
        = 0.632 (60 V / R)
        = ........... A
   back =  L (I /t)
            =........ V
(c)
   B / t = (B) A/ t
                 = (1 / 2) [o n (I)] A / t
                  =.......... V
(d)
   I = coil / Rcoil
     = Ncoil (B /t) / Rcoil
     = ......... A