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6.A solenoid of radius 1.50 cm has 600 turns and a length of 15.0 cm. (a) Find i

ID: 1522650 • Letter: 6

Question

6.A solenoid of radius 1.50 cm has 600 turns and a length of 15.0 cm.

(a) Find its inductance. ______mH

(b) Find the rate at which current must change through it to produce an emf of 90.0 mV. (Enter the magnitude.) ______A/s

7.The current in a 60.0-mH inductor changes with time as i = 4.00t2 5.00t, where i is in amperes and t is in seconds. (a) Find the magnitude of the induced emf at t = 1.00 s. _______mV

(b) Find the magnitude of the induced emf at t = 4.00 s. _______mV

(c) At what time is the emf zero? __________s

Explanation / Answer

6)

a)

Given:-

N = 600,

r = 0.015 m,

d = 0.15 m,

o = 4 x 10^-7 H/m

The inductance of a solenoid is given by:
L = oN^2A/d

L = oN^2(r^2) / d

L = (4 x 10^-7) x 600^2 x 3.14 x 0.015^2 / 0.15

L = 2.1297 mH

b)

emf = L (delta I /delta t)

90 x 10^-3 = 2.1297 x 10^-3 ( delta I /delta t)

delta I / delta t = 42.26 A/s

7)

V(t) = L(dI/dt)

V(t) = (60 x 10^-3 H)(8t - 5 s)

a)

V(1) = (60 x 10^-3 H)(8 - 5 s)
V(1) = - 0.180 V

(b)

V(4) = (60 x 10^-3 H)(4*8 - 5 s)
V(4) = 1.62 V

(c)

0 = (60 x 10^-3 H)(8t - 5 s)
0 = 8t - 5
t = 0.625 s