Question

What does the inductor behave as for a DC source?

Answer 1

When a DC (Direct Current) source is applied to an inductor, the inductor initially resists changes in current but eventually behaves as a short circuit after a long period of time.

Here’s a more detailed breakdown:

1. At the moment the DC source is applied: The inductor resists changes in current due to its property called inductive reactance. The inductor opposes any sudden increase in current, so it acts like a resistor. The current doesn't immediately rise to its final value but increases gradually. This is because the inductor generates a back EMF (electromotive force) that opposes the change in current.
   

1. After a long time: Once the current has stabilized (after a long time, when the transient effects have died down), the inductor behaves like a simple wire with very little resistance, or in other words, a short circuit. This happens because the inductor's opposition to the current (its inductive reactance) becomes zero for a DC source.
   

   - The voltage across the inductor becomes zero (since \( V_L = L \cdot \frac{di}{dt} \), and \( \frac{di}{dt} = 0 \) in a steady state for DC), meaning the inductor no longer resists the current flow.
   
   - The current will then flow freely through the inductor as it would through a regular conductor.

In summary:

1. Short-term (when the DC is first applied): The inductor opposes changes in current (acts like a resistor).
   

1. Long-term (after the current has stabilized): The inductor behaves like a short circuit with no resistance.