42. During periods of time when the current is varying linearly with time, Eq. 31-37 (in absolute values)

becomes

|E| = L

∆i
∆t

. For simplicity, we omit the absolute value signs in the following.

(a) For 0 < t < 2 ms

E = L

∆i

∆t

=

(4.6 H)( 7.0 A

− 0)

2.0

× 10

−3

s

= 1.6

× 10

4

V .

(b) For 2 ms < t < 5 ms

E = L

∆i

∆t

=

(4.6 H)( 5.0 A

− 7.0 A)

(5.0

− 2.0)10

−3

s

= 3.1

× 10

3

V .

(c) For 5 ms < t < 6 ms

E = L

∆i

∆t

=

(4.6 H)( 0

− 5.0 A)

(6.0

− 5.0)10

−3

s

= 2.3

× 10

4

V .