Around a charged rod there is a region where a charged scrap of foil feels a force without touching. Is that region a field?
Earth holds the Moon in orbit across 380,000 kilometers of empty space. Nothing stretches between them: no rope, no rod, no air. So what, exactly, exerts the force on the Moon?
The field idea answers it. The field is not just a label for a region of space. The field is the thing that acts.
Start with the thing that makes the field. Earth makes the gravitational field around it. A magnet makes the magnetic field around it. A charged balloon makes the electric field around it. The thing that makes a field is called the field's source.
Now comes the key move.
That sentence carries two separate steps. Step one: Earth creates the field, everywhere in the space around Earth.
Step two: the Moon sits inside that field. So the field, right there at the Moon, exerts the force on the Moon.
This is why the objects never need to touch. Earth does not reach across space. The field is already at the Moon, and the field does the acting.
A charged rod lifts a charged scrap of foil without touching it. What exerts the force on the scrap?
The same two steps run for every field.
A magnet holds a steel pin in the air, 1 centimeter below it. What exerts the upward force on the pin?
The magnet creates a magnetic field in the space around it.
The pin sits inside that field.
So the field exerts the force on the pin.
The magnet's field exerts the force on the pin.
Marta says a space station inside Earth's field feels a force from the field itself, not from anything touching it. Is Marta correct?
A charged balloon is brought near a second charged balloon, and the second balloon swings away without being touched. What exerts the force on the second balloon?
The first balloon creates an electric field in the space around it.
The second balloon sits inside that field.
So the field exerts the force on the second balloon.
The first balloon's field exerts the force on the second balloon.
Kofi says Earth cannot pull a satellite, because nothing stretches from Earth to the satellite. Is Kofi correct?
A magnet pulls a steel pin across 2 centimeters of empty air. Why does the pin feel a force with nothing touching it?
A charged strip of tape hovers above a second charged strip without touching it. What exerts the upward force on the hovering strip?
Which statement puts the source, the field, and the force in the right order?