When
an electric current is flowing through an inductor, there is energy stored in
the magnetic field. Suppose that an inductor of inductance L is connected to a variable
DC voltage supply, the supply is adjusted so as to increase the current I
flowing through the inductor from zero to some final value I. As the current
through the inductor is ramped up, an e.m.f. V = -Ldi/dt is generated, which
acts to oppose the increase in the current.
an electric current is flowing through an inductor, there is energy stored in
the magnetic field. Suppose that an inductor of inductance L is connected to a variable
DC voltage supply, the supply is adjusted so as to increase the current I
flowing through the inductor from zero to some final value I. As the current
through the inductor is ramped up, an e.m.f. V = -Ldi/dt is generated, which
acts to oppose the increase in the current.
Considering
the pure inductor of inductance L, the instantaneous power which must be supplied
to initiate the current in the inductor is P = iv = Lidi/dt
the pure inductor of inductance L, the instantaneous power which must be supplied
to initiate the current in the inductor is P = iv = Lidi/dt
Clearly,
work must be done against this emf by the voltage source in order to establish
the current in the inductor. The work done by the voltage source during a time
dt is
work must be done against this emf by the voltage source in order to establish
the current in the inductor. The work done by the voltage source during a time
dt is
Here
P = -IV is the instantaneous rate at which the voltage source performs work. To
find the total work done (W) in establishing the final current (I) in the
inductor, we must integrate the above expression. Thus;
P = -IV is the instantaneous rate at which the voltage source performs work. To
find the total work done (W) in establishing the final current (I) in the
inductor, we must integrate the above expression. Thus;
This
energy is actually stored in the magnetic field generated by the current
flowing through the inductor. In a pure inductor, the energy is stored without
loss, and is returned to the rest of the circuit when the current through the
inductor is ramped down, and its associated magnetic field collapses.
energy is actually stored in the magnetic field generated by the current
flowing through the inductor. In a pure inductor, the energy is stored without
loss, and is returned to the rest of the circuit when the current through the
inductor is ramped down, and its associated magnetic field collapses.
