In a field drawing of a straight current-carrying wire, the circles are drawn farther apart farther from the wire. What does that spacing show?
A compass 1 cm from a straight wire swings hard away from north. An electrician slides the compass out to 10 cm, leaving the current unchanged. The needle settles most of the way back toward north.
The needle swings less at 10 cm because the field there is weaker. The current did not change. Only the distance did.
You have already seen this in the drawing: the circles sit farther apart farther out, and wider spacing means a weaker field.
The fading also explains the needle settling back toward north. Far from the wire, the wire's field has grown weak, and Earth's field is the stronger one at the compass. So the needle swings most of the way back.
A compass slides farther from a wire, current unchanged. What happens to the field at the compass?
A compass slides closer to a wire, current unchanged. What happens to the field at the compass?
A compass is moved from 3 cm to 12 cm from a wire, at a fixed current. What happens to the field at the compass?
The field around a wire weakens with distance from the wire.
12 cm is farther from the wire than 3 cm.
The field at the compass gets weaker.
A sensor is moved from 20 cm to 2 cm from a cable. What happens to the field at the sensor?
Closer to the wire, the field is stronger.
2 cm is much closer to the cable than 20 cm.
The field at the sensor gets stronger.
Wren says a wire's field at 10 cm is weaker than at 1 cm. Is Wren correct?
Two compasses sit near one wire: one 2 cm out, one 6 cm out. Which sits in the stronger field?
A compass needle swings hard 1 cm from a wire, but barely moves 8 cm out. Why?
An engineer wants a stronger field at a sensor near a wire, without changing the current. What should she do?