Back in the Circuits topic, you saw that an electric current is the rate of flow of electric charge. This lesson adds what every current does to the space around it.
The wire itself is not a magnet. It has no iron and no poles. The current alone makes the field, and when the current stops, the field is gone.
A straight wire is joined to a battery through a closed switch. Is there a magnetic field in the space around the wire?
The circuit is complete, so a current flows in the wire.
An electric current produces a magnetic field in the space around it.
Yes. While the current flows, a magnetic field fills the space around the wire.
The same wire is then disconnected from the battery. Is there still a magnetic field around it?
With the battery disconnected, no current flows in the wire.
The field is there only while the current flows.
No. With no current, there is no magnetic field around the wire.
What does an electric current produce in the space around its wire?
Jude closes a switch, sending a current through a bench wire. What does a compass beside the wire do?
Hana says a magnetic field fills the space beside a current-carrying wire. Is Hana correct?
Omar's compass needle, lying beside a machine's supply cable, swings the moment the machine is switched on. What does this show about the cable?
Which of these has a magnetic field in the space around it?
Petra says a wire can affect a compass needle only if the wire is made of a magnetic material. Which observation proves her wrong?