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The windings of a circular cylindrical solenoid have 1369 turns per meter and cr

ID: 1567465 • Letter: T

Question

The windings of a circular cylindrical solenoid have 1369 turns per meter and cross-sectional radius r = 3.99 cm. A second coil having 120 loops is wrapped around the solenoid. The current in the solenoid increased from zero to t = 0.93 A in elapsed time Delta t = 1.60 times 10^3 seconds. a) Calculate the initial and final magnetic fields produced by the solenoid. b. Calculate A, the area of the solenoid cross-section. c. Calculate Delta Phi_g, the change in magnetic flux through the solenoid. d. Calculate the induced emf in the coil wrapped around the solenoid. e) Calculate M, the mutual inductance between the solenoid and the coil wrapped around it.

Explanation / Answer

let

n = 1369 turns/m

r = 3.99 cm = 0.0399 m

N = 120 turns

I = 0.93 A

delta_t = 1.6*10^-3 s

a)

Bi = mue*n*Ii

= 0

Bf = mue*n*If

= 4*pi*10^-7*1369*0.93

= 1.60*10^-3 T

b) A = pi*r^2

= pi*0.0399^2

= 5.00*10^-3 m^2

c) the change in flux through the solenoid = A*(Bf - Bi)

= 5*10^-3*(1.6*10^-3 - 0 )

= 8.00*10^-6 T.m^2

d) induced emf in the coil = N*change in megnctic flux/time taken

= 120*8*10^-6/(1.6*10^-3)

= 0.60 V

e) use induced emf = M*dI/dt

==> M = induced emf/(dI/dt)

= 0.6/(0.93/(1.6*10^-3))

= 1.03*10^-3 H