Chapter 34 Flashcards
(68 cards)
Heat flows through a conductor when…
a difference in temperature exists between its ends
Heat flows from…
the end of higher temperature to the end of lower temperature.
When both ends reach the same temperature…
the flow of heat ceases
When the ends of an electric conductor are at different electric potentials…
charge flows from one end to the other
When does charge flow?
when there is a potential difference, or difference in porential (voltage), between the ends of a conductor
Until when will the flow of charge end?
when both ends reach a common potential
When there is no potential difference…
there is no longer a flow of charge through the conductor
To attain a sustained flow of charge in a conductor…
some arrangement must be provided to keep one end at a higher potential then the other. The situation is analogous to the flow of water from a higher reservoir to a lower one. Water will flow in a pipe that connects the reservoirs only as a difference in water level exists.
The flow of water in the pipe, like the flow of charge in the wire that connects the Van ge Graaff generator to the ground, will cease when…
the “pressures” at the two ends are equal
In order that the flow be sustained…
there must be a suitable pump of some sort to maintain a difference in water levels. Then there will be a continual difference in water pressures and a continual flow of water. The same is true of electric current
What is electric current?
The flow of electric charge
In solid conductors the electrons…
carry the charge through the circuit because they are free to move throughout the atomic network.
What are electrons in solid conductors called?
conduction electrons
What is electric currents charged in?
Amperes
Whats is an ampere?
The flow of 1 coulomb of charge per second
A current-carrying wire has a net electric charge of…
zero
While the current is flowing…
negative electrons swarm through the atomic network that is composed of positively charged atomic nuclei
When electrons flow in a wire…
the number entering one end is the same as the number leaving the other. So we see that the net charge of the wire is normally at every moment
Charges do not flow unless…
there is a potential difference
A sustained current requires a…
suitable “electric pump” to provide a sustained potential difference.
What is a voltage source?
Something that provides a potential difference
What happens if you charge a metal sphere positively and another negatively? Why is this not a good voltage source?
You can develop a large voltage between them. This is not a good voltage source b/c when spheres are connected by a conductorm the potentials equalizr in a single brief surge of moving charges
Voltage sources such as batteries and generators supply…
energy that allows charges to move steadily
In a battery a chemical reaction occuring inside releases…
electrical energy
