Final answer:
To find the energy stored in the 20mH inductor, use the formula E = 1/2 * L * I², where L is the inductance and I is the current.
Step-by-step explanation:
The energy stored in an inductor can be calculated using the formula E = 1/2 * L * I², where E is the energy, L is the inductance, and I is the current. In this case, the inductance of the 20mH inductor is given as 20mH. To find the energy, we need to determine the current flowing through the inductor. If the current is not given, we cannot calculate the energy.
However, if the current is given, we can use the formula E = 1/2 * 20mH * I² to find the energy stored in the inductor.