Flashcards in Electricity Deck (15):
What is a coulomb?
One coulomb is the amount of charge which flows past a point when a current of one amp flows for one second
What is Kirchhoff's 1st law?
It states that the sum of the currents flowing into any point in on a circuit is equal to the sum of the currents flowing out of that point
What is a volt?
One volt is one joule per coulomb
What is electromotive force (emf)?
The energy transferred per unit charge when one other type of energy is converted into electrical energy
What is potential difference?
The electrical energy transferred per unit charge when electrical energy is converted into another form of energy
What is resistance?
The resistance of a component is the ratio of potential difference across the component to the current flowing through it
What is resistance caused by?
Resistance is caused by collisions between free electrons and the metal ions
What factors cause resistance to increase?
If the length increases, temperature increases, or cross sectional area decreases
What is Ohm's law?
For a conductor at constant temperature, the current in the conductor is proportional to the potential difference across it
Why does an increase in length of a wire cause increased resistance?
It increases the chance of collisions
Why does an increase in temperature cause increased resistance?
Higher temperature means the ions move more, increasing the chance of collisions
Why does increased cross-sectional area cause decreased resistance?
There are a greater number of possible routes for electrons to take and so there is a lower chance of collisions (cross sectional area is inversely proportional to resistance)
What is conventional current?
Flow of charge, opposite to electron flow
What is current?
Electric current is the flow of charged particles per unit time