Electrical Circuits Flashcards
Define EMF:
the amount of energy put in the circuit per coulomb of charge
Define Pd:
the amount of energy taken out the circuit per coulomb of charge
How is EMF lost within circuits?
transferred as heat energy and lost through internal resistor
What is the equation of the graph that includes internal resistance?
V=-Ir+EMF
What is an electron gun?
electrical device used to produce a narrow beam of electrons
What is an electron gun used for?
to ionise particles by adding or removing electrons
What is work done on the electron equal to?
gain in kinetic energy
How does thermonic emission work?
A small metal filament acts as a cathode, is heated by passing a pd through it. Some electrons gain enough kinetic energy to escape the metal.
Why is the circuit of an electron gun in a vacuum tube with a high pd between the filament and the anode?
freed electrons can accelerate towards the anode
Why does the anode of an electron gun have a small hole in it?
so that a beam of electrons can pass through at a specific kinetic energy
What does a potential divider consist of?
two or more resistors in series with each other and with a source of fixed potential difference
What do potential dividers do?
divide potential difference between components in the circuit
What does a potentiometer do?
supplies a variable output potential difference
What is a potentiometer?
coiled wire in a tube
What is an example of a potentiometer?
dimmer switch
