Step-by-step explanation:
We can use Faraday's law of electromagnetic induction to find the average induced emf in the coil. According to this law, the induced emf (ε) in a coil is equal to the negative of the rate of change of magnetic flux through the coil:
ε = - dΦ/dt
where Φ is the magnetic flux through the coil.
The magnetic flux through a coil of inductance L is given by:
Φ = LI
where I is the current in the coil.
Differentiating both sides of this equation with respect to time, we get:
dΦ/dt = L(dI/dt)
Substituting the given values, we get:
dI/dt = (1.50 A - 0.200 A) / 0.250 s = 4.40 A/s
L = 3.00 mH = 0.00300 H
Therefore, the induced emf in the coil is:
ε = - L(dI/dt) = - (0.00300 H)(4.40 A/s) = -0.0132 V
Since the question asks for the magnitude of the induced emf, we take the absolute value of the answer and convert it from volts to millivolts:
|ε| = 0.0132 V = 13.2 mV
Therefore, the magnitude of the average induced emf in the coil for the given time interval is 13.2 mV.