# What is the polarity of inductor acting as a current source when connected to a DC source?

#### Devika B S

Joined Mar 8, 2017
144
From what I understand, the polarity of inductor is opposite to that of the initial DC source connected to it. For example, in the diagram above, I hope the current direction shown in mode 2 (the second diagram) is correct and not in the opposite direction. However, while writing equations, this negative sign is neglected as only (del I) is written.

Joined Jul 18, 2013
20,405
The induced voltage at switch off is of opposite polarity to the applied voltage.
Max.

#### AlbertHall

Joined Jun 4, 2014
9,626
The induced voltage at switch off is of opposite polarity to the applied voltage.
Max.
But the current wants to continue flowing in the same direction.

#### Devika B S

Joined Mar 8, 2017
144
But the current wants to continue flowing in the same direction.
But once disconnected, now the polarity of the inductor being in the reverse direction; the current is supposed to flow in opposite direction (as current always flows from positive to negative). Right? Isn't this how switched mode converters like Buck converters work?

#### crutschow

Joined Mar 14, 2008
24,709
You might think of the current in the inductor as an inertial mass.
You have to push to get the mass moving, and when you stop pushing, it wants to keep moving in the same direction.
You have to apply a force in the opposite direction to slow it down (similar to the reversed voltage with the inductor when the voltage is removed).

#### crutschow

Joined Mar 14, 2008
24,709
But once disconnected, now the polarity of the inductor being in the reverse direction; the current is supposed to flow in opposite direction (as current always flows from positive to negative). Right? Isn't this how switched mode converters like Buck converters work?
No and no.
The reversed voltage slows down the current but it doesn't reverse it.
In a Buck converter, the current is always moving the same direction through the inductor.