To solve the problem it is necessary to apply the concepts related to Voltage in an Inductor. By general definition the voltage in in an inductor is defined as
[tex]\epsilon = L \frac{di}{dt}[/tex]
Where,
[tex]\epsilon =[/tex]Voltage induced (emf)
L = Inductance
di = Rate of change of current flow
dt = rate of change of time
Our values are given by
[tex]L = 2mH = 2*10^{-3} H[/tex]
[tex]\Delta i = i_2-i_1 = 1.5A-0.2A = 1.3A[/tex]
[tex]\Delta t = 0.3s[/tex]
Replacing
[tex]\epsilon = 2*10^{-3}*\frac{1.3}{0.3}[/tex]
[tex]\epsilon = 8.6*10^{-3}V[/tex]
[tex]\epsilon = 8.6mV[/tex]
Therefore the magnitude of average induced emf is 8.6mV
