Fields & Static Flashcards
All 5 cards in this deck
What are the steps to explain why a spark jumps between a charged object and an earthed conductor?
e.g. a negatively charged rod held near an earthed metal conductor
- The large potential difference creates a strong electric field, so the air breaks down (ionises).
- Electrons move through the air — there is a current in the air.
- They move from the rod to the earthed conductor, seen as a spark.
What happens to air when the electric field around a charged object becomes very strong?
The air becomes ionised (breaks down) so it conducts charge.
How can a person flying a kite very close to (but not touching) an overhead power cable receive a shock?
The electric field strength is very high, so the air is ionised and conducts charge through the kite and string to the person/earth.
A student touching a negatively charged dome finds her hair stands on end. What causes this?
Electrons are transferred to her, so each hair is negatively charged, and like charges repel.
As the distance between a charged object and earth increases, what happens to the potential difference needed for a spark to jump?
It increases.
A bigger gap needs a bigger potential difference before the air breaks down and conducts.