Question

Does self inductance occur if DC current is passed?

Answer 1

Yes, self-inductance can occur when DC (Direct Current) flows through a coil or inductor, but it only happens momentarily during the time when the current is changing.

Here’s a breakdown:

1. Self-inductance is the property of a coil or inductor to oppose changes in the current passing through it. This happens because any change in current creates a changing magnetic field around the coil, which induces a voltage (also called emf) that opposes the change in current, according to Faraday’s Law of Induction.
   

1. When a DC current is first applied to an inductor, the current starts at zero and increases gradually. During this period of change, the inductor will oppose this change, and self-inductance comes into play, creating an opposing voltage.
   

1. Once the DC current reaches a constant value (after the initial ramp-up period), the current no longer changes, and the voltage induced by the inductor drops to zero. At that point, there’s no self-inductance effect because there is no change in the current anymore.
   

In short, self-inductance is significant only when there is a change in current. Once the current becomes constant (in the case of DC), the inductance doesn’t produce any opposition to the current anymore.