Topic 3 - Electric Circuits Flashcards
Why does electric charge exists?
Electric charge exists because of the electrostatic force experienced by a charged particle
What does the conservation of charge law state?
The conservation of charge law states that the total electric charge in an isolated system never changes. Hence the net quantity of electric charge, the amount of positive charge and negative charge in the universe, is always conserved.
What is an electric current?
Electric current is the rate of flow of charge or the amount of charge per second flowing past a given point
What is the formula that links electric current, electrical charge and a change in time?
I = Q/T
What is the component used to measure current, how should it be connected in a circuit and what should it’s resistance be?
Ammeter measures current and is connected in series with the component being measured. The resistance of the ammeter must be very low.
What happens to current in a series circuit and at junctions in a parallel circuit?
In a series circuit the current is the same in each component. In parallel, the current at a junction will split according to the resistance along each branch.
Why is a material suitable to allow current to flow through it?
In order for a current to follow in a material, suitable charge carriers must be present within the material.
What is a charge carrier?
A charge carrier is either an electron that is detached (delocalised) from its atom or an ion in a conducting material that is free to flow in order to create a current.
What does the short and long lines in a battery on a circuit diagram represent?
In a cell or battery the shorter line is the negative terminal and the longer line is the positive terminal.
What is electron flow?
Electron flow is the movement of electrons; from the negative terminal to the positive terminal
What is the conventional current?
Conventional current flow is the movement of positive charge carriers; from the positive terminal to the negative terminal
Why are metals suitable for current to flow through it?
A metal conductor contains charge carriers that are loosely bound outer electrons called delocalised electrons that have donated valence electrons. Depending on the type of metal, there can be multiple delocalised electrons per atom.
Describe the movement of electrons within a metallic conductor?
In a metallic conductor these electrons move with random thermal motion, to and fro within a crystal lattice.
With reference to electrons why are metals good conductors of heat?
Metals are good conductors of heat as the electrons are free and fast moving so can transfer energy quickly to the metal lattice ions when they collide, which causes the metal to heat up faster.
What happens when a potential difference is applied to a circuit, in terms of electrons?
When a potential difference is applied to a circuit (energy is given to the electrons), a force is exerted on the electrons, which causes them to “drift” in the direction of the force.
