A long, fine wire is wound into a coil with inductance 5 mH. The coil is connect

Question

A long, fine wire is wound into a coil with inductance 5 mH. The coil is connected across the terminals of a battery, and the current is measured a few seconds after the connection is made. The wire is unwound and wound again into a different coil with L = 10 mH. This second coil is connected across the same battery, and the current is measured in the same way. Compared with the current in the first coil, is the current in the second coil four times as large unchanged      one-fourth as large

Explanation / Answer

The only way dI/dt can be constant is if the current is changing. The coil can retain its back-emf only if it draws current, and that current must steadily increase with time.
Once a single charge carrier crosses the line, a change in current has happened and the process has begun.

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