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So initially S1 and S4 are closed and current flows as seen above.

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After some time S1 and S4 are open and current flows as seen above. Now I am confused about the polarity of the inductor, what if I said the current flows through D1 and D4 instead of D3 and D2 ?, would that be wrong ?

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Yes, you are wrong. The current enters the coil from the left while S1 and S4 are closed. If S1 and S4 are open, the coil will produce a voltage with the plus in its right so to mantain the current previous to the disconnection. That current will flow thru D2 and D3

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what if I said the current flows through D1 and D4 instead of D3 and D2 ?, would that be wrong ?

Yes, that would be wrong. The polarity on the inductor reverses when the switches are opened. Why?

When the inductor is powered from the voltage source, current flows in the direction shown. As the inductor is a load its polarity must follow the current from positive to negative.

When power is removed the inductor won't let the current drop instantly to zero. Any drop causes it to generate a voltage which tries to keep the current flowing in the same direction. However as it is now acting as a voltage source rather than a load, the polarity must be reversed (positive on the right and negative on the left) as it pushes current out into the circuit.

Actually, any time current changes in an inductor, it generates a voltage that opposes the change. When power is first applied in your circuit the inductor will oppose the rising current by generating a voltage equal to the supply voltage - this time with the same polarity as the power supply - but always in the same direction relative to the current change.

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