Hana says a magnetic field fills the space beside a current-carrying wire. Is Hana correct?
A compass sits 2 cm from a straight wire. An electrician turns a dial that sets the wire's current. At 0.5 A the needle barely swings. At 5.0 A the same needle swings hard away from north.
The needle swings further when the field at the compass is stronger. Nothing moved between the readings. Only the current changed. So the current sets the field's strength.
The dial has a bottom end too. With no current at all, there is no field: the needle returns to pointing north. This holds for any wire. Turn the current up, and its magnetic field strengthens.
The current in a wire is doubled. What happens to the field around it?
A dimmer cuts a lamp cord's current. What happens to the field around the cord?
The current in a wire is turned up from 1.0 A to 4.0 A. What happens to the magnetic field around the wire?
More current makes a stronger magnetic field.
4.0 A is more current than 1.0 A.
The field around the wire gets stronger.
A heater cord's current falls to half its value. What happens to the field around the cord?
Less current makes a weaker field.
The field around the cord gets weaker.
The current in a wire is switched off. What happens to the field around it?
Which change makes the field around a wire stronger?
Three wires carry 1.5 A, 3.0 A, and 6.0 A. Which has the strongest field just outside it?
The field around a wire weakened, though nothing around the wire moved. What happened to the current?