Induced current in long straight wire

[w3390]

Homework Statement

A current is induced in a loop by something happening with current in a long straight wire near the loop. What could be happening? (There are two possibilities. Neither the wire nor the loop is moving.)

Homework Equations

Ampere's Law
Faraday's Law

The Attempt at a Solution

I'm pretty sure I know one of the possibilities. I said that one possibility is that the current in the straight wire is changing. This changing current will create a magnetic field. This created magnetic field will then induce a current in the loop. I cannot think of the other possibility if the wire and loop are not moving. Any help would be appreciated.

 

[Dadface]

The only other possibility I can think of is that the straight wire is fed by a d.c. supply which is then switched on or off the current in the coil being induced at those instants.I do not like this answer, however, because the current does change momentarily during switching and you have already described a changing current.