Boxi Learn › Physics › Stage 4 · Systems and Argument
Drawing a force you cannot see
PHY-3 Fields push and pull across empty spaceX-3 Look from another side
What many people think
Charges only feel a force when they touch.
The idea
Field lines leave positive charges and end on negative ones; where they crowd together the force on a test charge is strongest.
Explain it
A friend says a charged balloon can only move a scrap of paper if they touch. Using the words “field”, “line” and “distance”, explain what you would see as the balloon comes closer, and why.
Try at home
Rub a balloon on wool or dry hair, then bring it slowly toward tiny bits of tissue paper, or toward a thin stream of tap water. Notice how far away it starts to act, and how much faster the effect grows as it gets closer. Works best on a dry day.